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I would like to write a simple in-house program that parses user commands written in a language of our team's own invention (but based closely on another program we are already familiar with). The command parser that I am working on now will simply be the UI through which the user can run the other algorithms I have already written. (Those other algorithms, by the way, are used to generate the input files for a molecular dynamic simulation package called LAMMPS.) The only thing I really have left to do is just write this UI, but as it turns out, writing your own scripting language is almost an intractable challenge for a non software engineer to tackle on his own.
According to the answers I received, what I am try to make would be considered a Domain Specific Language, and it is not advisable to try to make one's own DSL due to the enormous amount of work required to make it useful and bug-free.
The best option then would actually be to use an existing scripting language like Lua or Python, and embed it in the program.
To do this, I will most likely use Lua because it seems most fitting for our needs. So at this point, the rest of this question is no longer relevant since the answer would be: "Don't do it yourself." But I'm still going to keep part of it here for other users to be able read and learn from the wonderful answers below.
Thanks again to everyone who replied!
Old Question:
I would like to write a program that parses a user text input and then
runs a function corresponding to that input. To do this I would need
to parse the string for relevant keywords. I believe there will be
less than 15 keywords when I'm done, so ideally I'd like this code
to be simple and short.
The problem is that I am currently using if-statements to parse the
strings. This is an extremely inconvenient way to parse commands
because even for a short 3 word commands the code explodes into nested-ifs
3 layers deep. So longer 8+ word sentences will become nested-ifs more than
8 layers deep.
This kind of programing approach quickly becomes unmanageable, especially
when I need to make any significant changes to a command.
My question is whether or not there exists a data structure in C++ that
can help me better manage my giant nested-ifs, or if anyone could suggest
a better way to parse a string for lots of different data types (i.e.
substings, ints, and floats) and output an error message when the expected
type is not found?
Here is an example of a short user session to show the kinds of commands
I would like to interpret:
load "Basis.Silicon" as material 1
add material 1 to layer 1
rotate layer 1 about x-axis by 45 degrees
translate layer 1 in x-axis by 10 nm
generate crystal
These commands are based on an already-existing program that our team
uses, but unfortunately the source code for this program has never been
publicly released so I am left guessing as to how it was actually
implemented.
One final note, unlike natural language processors, I know exactly what
the format of each line will be. So my issue isn't so much how to interpret
the text, but rather how to code the logic in a concise and manageable way.
Thanks everyone!
Your question is not clear. And your goals are more difficult than what you believe.
Either you consider that you want to somehow process human language sentences (e.g. in English). Then you want to study natural language processing, and you can find some libraries related to that field.
Or you consider that you want to interpret some formal programming or scripting language. Then you want to study interpreters and compilers. BTW, in that case, you might just embed an existing interpreter (like Lua, Guile, Python, etc....) in your program.
You could also think in terms of expert systems with a knowledge base made of rules (this approach could be viewed as in the middle between NLP and scripting language) You'll then need some inference engine (perhaps CLIPS). See also J.Pitrat's blog.
Notice that even coding a simple interpreter is more difficult than you believe. You absolutely need to represent abstract syntax trees, which you construct from textual input with a parsing phase.
BTW, All of NLP, expert systems, and interpreter design and implementation are difficult fields. You could get a PhD in all 3 fields (but you have to choose which).
If you go the embedded interpreter way: study the interpreters I mentioned (Guile, Lua, Python, Neko, etc...) and choose which one you want, to embed.
If for whatever reason, you want to make an interpreter from scratch: Learn several programming languages first (including scripting languages like Ruby, Python, Ocaml, Scheme, Lua, Neko, ...). Read books on Programming Language Pragmatics (by M.Scott) and Lisp In Small Pieces (by Queinnec). Read also text books on compilation and parsing, and on Garbage Collection and formal (e.g. denotational) semantics. All this may need a dozen years of work.
Notice that by experience embedding a software in an interpreter is a very structuring design. If you did not thought of that at the beginning you probably need to redesign and refactor a lot your existing application. For instance, when embedding a software in an interpreter, you cannot afford that bad input crashes the program. So error handling and memory management (interfacing to the GC of the interpreter) is challenging and gives new constraints. Hence you'll need to re-think your application.
If all this is new (and even if you don't choose e.g. Guile as the embedding interpreter): learn and practice a bit of Scheme -e.g. with Guile or PltScheme- (e.g. reading SICP), read a little bit about λ-calculus and closures, then read Queinnec's Lisp In Small Pieces book. Remember the halting problem (which is partly why interpreters are difficult to code).
BTW the syntax you are proposing (e.g. rotate mat 1 by x 90) is not very readable and looks COBOL-like. If possible, have a language which looks familiar to existing ones. Make it easy to read !
Start by reading all the wikipages I am referencing here.
FWIW, I am the main author of MELT, a domain specific language (inspired a lot by Scheme) to extend the GCC compiler. Some of the papers / documentations I wrote might inspire you (and contain valuable references).
Addenda (after question was reformulated)
You seems to invent some formal syntax like
add material 1 to layer 1
rotate layer 1 about x-axis by 90 degrees
translate layer 1 in x-axis by 10 inches
I can't guess what kind of language is it? Are you implementing a 3D printer? If yes, you should stick to some existing standard formal language in that domain.
I believe that such a COBOL-like syntax is really wrong. The point is that it is too verbose, and that you are wishing to implement some domain specific language. I find your example very bad-looking.
Is that syntax your invention, or is there some document specifying (and many thousands already existing lines coded in) your domain specific language. If you are just inventing it, please reconsider the syntax and the semantics.
First, you need to specify on paper the full syntax and semantics of your DSL.
Is your DSL Turing complete? (I guess that yes, because Turing completeness is reached very quickly - e.g. with variables and loops....). If yes, you are inventing a scripting language. Please don't invent scripting language without knowing several programming & scripting languages (then read Programming Language Pragmatics...). The point is that, if your scripting language will become successful, advanced users will soon or later write important programs in it (e.g. many thousand lines). Then, these advanced users will be programmers. In that case, it is very important (for social & economic reasons) to have a DSL well founded and looking familiar (if possible, an extension of some existing scripting language).
If your DSL already exists, stick to its specification on paper. If that specification is not good enough, improve it with formalization (e.g. by writing some BNF syntax, and some formal (e.g. denotational) semantics for it). Publish and discuss that formalization with existing users.
Several industries got some ad-hoc DSLs which became widely used but was ill designed
(e.g., in the French nuclear industry, the Gibiane DSL designed in the 1970s by nuclear physicists, not computer scientists; the US Boeing corporation is also rumored to have made similar mistakes). Then, maintaining and improving the many hundred thousands lines of DSL scripts is becoming a nightmare (and may means losing millions of dollars or euros). So you better stick to some existing scripting language. The advantages are that there exist some culture on it (e.g. you can find dozens of books on Python or Lua, and many trained engineers familiar with them), that the interpreter is widely used and tested, that the community working on them is improving the interpreters, so it has quite few uncorrected bugs.
You should not attempt to design and implement your own DSL if you are not a trained computer scientist. Stick to some existing scripting language (of course their syntax is not like you want it to be), and leverage on existing implementations and experiment.
As a counter-example, J.Ousterhout has invented the widely used Tcl scripting language, with the claim that scripts are always small (e.g. hundreds of line only) and won't grow to big code base; unfortunately, some of them did, and Tcl is known as a bad language to code many dozens of thousands of lines (even if Tcl is an easy and convenient language for tiny scripts). The moral of the story is that if a (turing complete) scripting language is becoming successful, some "crazy" advanced user will code hundred of thousands of script code. So you need that scripting language to be well designed from the start. Hence, you should adopt and adapt a good existing scripting language (and avoid inventing an unfamiliar syntax without having a good knowledge of several existing scripting languages)
later additions
PS: my criticism of Tcl is not entirely subjective: the point is that Tcl was designed for small scripts in mind (read J.Ousterhout's first papers about Tcl), but my point is that when you offer a Turing-complete scripting language, some "crazy" user will eventually write huge scripts for it. Hence, you need to anticipate such "crazy" usage by offering a scripting language which "scales up" to big scripts, so is built according to software engineering practices for large software code base.
NB. Lua is probably a good choice as a language to embed. It is small, has a nice implementation, is well documented, and has good performance. But be careful about memory management issues (and this advice holds for any scripting language).
EDIT: To be more clear, I would like to have a short list of key words
(<15). The order/presence of which would determine which function will
be run.
You can build a small ruleset engine (e.g. something that processes lists of words). You write that engine/function once and just pass the data structures to it.
As an alternative, a solution using regular expressions would be probably the fastest to code (the engine is ready for you), assuming you're familiar with the regexp syntax (if not, it's still a good investment).
You could build a table of keywords and function pointers:
typedef void (*Function_Pointer)(void);
struct table_entry
{
const char * keyword;
Function_Pointer p_function;
};
table_entry function_table[] =
{
{"car", Process_Car},
{"bike", Process_Bike},
};
Search the table for a keyword. If the keyword is found, dereference the function pointer.
The following snippet will execute the function for processing the word "car":
(function_table[0].p_function)();
There is a famous program, called Eliza, which parses sentences for keywords.
Examples can be found at: Eliza C++ examples
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After a while surfing on source code of big projects especially application servers like this, I have understand these projects are not developing by one language. Many of them are using python for secondary language.
Now I have four questions:
Why is used more than one language?
Why python is used for secondary often?
Why python is not used to develop all parts of projects and they still is using c/c++?
And which the parts of projects should be developed with python and which part of projects is using c/c++?
Hard and soft layers
Programming language designs tend to trade off between "high-level" features, which enhance programmer productivity at the cost of speed, and "low-level" features, which require a great deal of programmer effort but produce very fast code.
Therefore it sometimes makes sense to use two languages on a project:
Write 90% of the code in an expressive, high level language which is easy to write and maintain.
Write the 10% of performance-critical code in a low-level language which is harder to write, but allows for comprehensive optimisation.
c2wiki calls this the HardAndSoftLayers pattern:
By virtue of the first rule of optimization, go ahead and write most of your code in the highest level language you can find.
By virtue of the third rule of optimization, when you must, use a profiler and find the slow parts of your program. Take those parts, and write them in a lower-level language.
For reference, the rules of optimisation are:
First Rule Of Optimization - Don't.
Second Rule Of Optimization - Don't... yet.
Profile Before Optimizing
The rule is pretty simple: the developers choose the language(s) based more or less on the following criterias:
their familiarity with it
how easily you can do the task using that language
how well is suited the language to the specific task
Today most of the development done in this multilingual environments are huge solutions, where different components need to communicate, exchange data or simply do work which is comprised of more than one step. It is easier to write the communication/data interpretation/whatever wrapping necessary part in a language such as python and then leave the real time and speed needy work to be done by some lower level language which compiles directly without the need for an interpreter.
Let's dig a little bit deeper.
How familiar are the developers with the programming language depends on the background of each developer. If they are given a free choice, obviously they will pick the language they know the best, unless there is a lobby from someone else... usually higher in the management chain. Python is not necessarily the language of choice, python is simply an easy to use and learn language, which is well suited for most tasks. Our project has no bit of python in it, only tons of ruby code. Because the main developer liked ruby at that time, so we're stuck with it.
If you know more than one programming language you know that each of them is doing the same thing differently. For example, creating a socket, connecting to a server, reading the stuff and printing it out is just a few lines of Erlang code, but it takes a lot more to do it in C++ (for example...) So again, if you have a task you know how to solve easily in a specific language you are going to stuck to it. People are lazy, they don't necessarily learn new stuff unless needed.
Obviously you are not going to write a device driver in python, and it is much easier to create a complete web service with java than with plain C... but you still would need the part of the solution that does the hardware close thing. When you have a task you carefully measure the requirements and implications and wisely choose the language you will do it in. Because it will stuck to it forever.
Sometimes python is not good enough.
Dealing with computer vision, image or sound processing, calculate tones of data is not really what python is good at. Other language like C or C++ is really good at those fields.
support your primary language is java, and you want to glue other languages into one project. That where we need Python. Python is well known glue language. you can use ctype,SWIG, Jython, ironPython or other method to bind multiple language.
Guess I answered this question at 1.
Need for speed. go for C or C++ . Care more about productivity, go with Python.
Without referring to the project you sent, I'll give you my 50c for why the company I work for, as to why we use python quite often in our projects.
Primarily, we have no python code relating to the software solution itself. All python code either relates to assist with development, machine set up, common framework tools deployment for testing, and vastly for code generation.
Why is used more than one language?
No project we work on has only one language, when looking at all our enterprise level solutions or large scale implementations.
This is mostly due to the fact that our tiers are written in languages that provide best performance and usability at each level separately.
For instance, C++ for speedy core back-end services, and C#.NET for rapidly developed and provide good UI for the front-end.
Why python is used for secondary often?
Personally, apart for the reasons I explained above, we don't make use of python 'secondary often'. We use C++/C# as the most common pair, but depending on the platform, might be other pairs.
Why python is not used to develop all parts of projects and they still is using c/c++?
Python is great for quick solutions and doing things you wish your shell could do. This largely involves file management, etc.
C++ is perhaps the fastest compiled language, providing optimal usage for core and largely used actions.
Based on that, and the fact that the market has more knowledge and experience in C++ (for many reasons), C++ is the more popular choice.
And which the parts of projects should be developed with python and which part of projects is using c/c++?
I believe I may have already addressed that above.
-
I hope I could help, please remember this is only my personal opinion and by no means should this be taken as a fact.
Now I'm generally in Java/C# (love both of them, can't really say I'm dedicated to one).
And I've recently been discussing the differences between F# and C# with a friend, when he surprised me saying: "So.. F# sounds a lot like lisp, but with way less 'Swiss-army knife' feel to it."
Now, I was partly ashamed of saying this but I have no idea what lisp was.
After some searching, I saw that lisp is very interesting, but got stumped by the multiple dialects and running environments.
Here is what I know:
I know of 3 dialects:
Common Lisp (I have the Practical Common Lisp book in my bookmarks.
Scheme (a more "theoretical" version of CL)
Clojure. Seems to be a version of CL that runs on JVM.
The basic idea of lisp seems to be about using code as data.
What I want to know:
What is the running environment for different dialects? How do they work/get installed (by this I mean is it a runtime like Java Virtual Machine, or if it requires something else, or if it's supported generally by the OS (as in compiled)). And how to get them (if something is to be gotten)
What is the better dialect to learn (I want the dialect not to be a "learning language" but one you can fully use afterwards without regret of not learning some other one, for example one should first learn C++ before trying out Visual C++, if you know what I mean)
What are the main advantages of lisp in general (I've seen many pages about that saying it's faster in development and execution, but they were all pretty vague about the details)
Can it be generally used for general purpose, or is it concentrated on AI? (By this I mean if, for example, one could make a full console app with it, and then implement OpenGL just as easily and make a game. Learning a language specialized on something precise is worthwhile, but not at the moment for me)
I would also be very happy about any additional details you guys can give me! (Links are appreciated too! E-Books and whatnot.)
Edit: all of the answers here were very useful. As such, I gave them all a +1 to rep, but chose the more concrete one as best. Thank you all.
I also learnt Java and C# intensively before coming to Lisp so hopefully can share some useful perspectives.
Firstly, all Lisps are great and you should definitely consider learning one. There's a famous quote by Eric Raymond:
"Lisp is worth learning for the profound enlightenment experience you
will have when you finally get it; that experience will make you a
better programmer for the rest of your days, even if you never
actually use Lisp itself a lot."
Reasons that Lisps are particularly interesting and powerful are:
Homoiconicity - in Lisp "code is data" - the language itself is written in Lisp data structures. In itself this is interesting, but where it gets really powerful is when you start using this for code generation and advanced macros. Some believe that this features is a key reason why Lisp can help you be more productive than anyone else (short Paul Graham essay)
Interactice development at the REPL - a few other languages also have this, but it is particularly idiomatic and deep-rooted in Lisp culture. It's remarkably productive and liberating to develop while altering a live running program. Recent examples that caught my eye include music hacking with overtone and editing a live game simulation.
Dynamic typing - opinion is more divide on whether this is an advantage or not (I'm personally neutral) but many people thing that dynamically typed langauges give you a productivity advantage, at least in terms of building things quickly. YMMV.
My personal recommendation for a Lisp to learn nowadays would be Clojure. Clojure has a few distinct advantages that make it stand out:
Modern language design - Clojure "refines" Lisp in a number of ways. For example, Clojure adds some new syntax for vectors [] and hashmaps {} in addition to lists (). Purists may disapprove, but I personally believe these find of innovations make the language much nicer to use and read.
Functional first and foremost - all the Lisps are good as functional languages, however Clojure takes it much further. All the standard library is written in terms of pure functions. All data structures are immutable. Mutable state is strictly limited. Lazy sequences (including infinite sequences) are supported. In some senses it feels a bit more like Haskell than the other Lisps.
Concurrency - Clojure has a unique approach to managing concurrency, supported by a very good STM implementation. Worth watching this excellent video for a much deeper explanation.
Runs on the JVM - whatever you think of Java, the JVM is a great platform with extremely good GC, JIT compilation, cross platform portability etc. This can be a barrier to entry for some, but anyone used to Java or C# should quickly feel at home.
Library ecosystem - since Clojure runs on the JVM, it can use Java libraries extremely easily. Calling a Java API from Clojure is trivial - it's just like any other function call with a syntax of (.methodName someObject arg1 arg2). With the availability of the huge Java library ecosystem (mostly open source) Clojure basically leapfrogs all the "niche" languages in terms of practical usefulness
In terms of applications, Clojure is designed to be a fully general purpose langauge so can be used in any field - certainly not limited to AI. I know of people using it in startups, using it for big data processing, even writing games.
Finally on the performance point: you are basically always going to pay a slight performance penalty for using higher level language constructs. However Clojure in my experience is "close enough" to Java or C# that you won't notice the difference for general purpose development. It helps that Clojure is always compiled and that you can use optional type hints to get the performance benefits of static typing.
The flawed benchmarks (as of early 2012) put Clojure within a factor of 2-3 of the speed of statically typed languages like Java, Scala and C#, a little bit behind Common Lisp and a little bit ahead of Scheme (Racket).
Lisp, as you've discovered, is not one language; it's a family of languages that have certain features in common.
There are two primary dialects of Lisp: Common Lisp and Scheme. Each of those two dialects has many implementations, each with their own features. However, both Common Lisp and Scheme are standardized, and the standards define a certain baseline of features which you can expect any implementation to have.
Scheme is a minimalistic language with a very small standard library. It is used primarily by students and theoreticians. Common Lisp has many more language features and a much larger standard library, including a powerful object system, and has been used in large production systems.
Clojure is another minor, more recent dialect. If you want to understand Lisp, you're better off first learning either Common Lisp or Scheme.
My recommendation is to learn Scheme first; it's a purer expression of the ideas that Lisp is made of, and will help you understand the essence of the language. In many ways, Lisp is completely different from Java and other imperative languages; however, what you learn from it will make you a better programmer in those languages. You can easily learn Common Lisp after you know Scheme.
The advantage of Lisp is, simply put, that it's more powerful than other languages. All Lisp code is Lisp data and can be manipulated as such; this allows you to do really cool things with metaprogramming that simply can't be done in other languages, because they don't give you direct access to the data structures that comprise your code. (The reason Lisp can do this and they can't is intimately related to its strange-looking syntax. Every compiler or interpreter, after reading the source code, must translate it into abstract syntax trees. Unlike other languages, Lisp's syntax is a direct representation of the ASTs that Lisp code is translated into, so you know what those trees look like and can manipulate them directly.) The most commonly used metaprogramming feature is macros; Lisp macros can literally translate a bit of source code into anything you can program. You can't do that with, say, C macros.
The "faster in development and execution" thing may have been a reference to one specific feature which most Lisp implementations provide: the read-eval-print loop. You can type an expression into a prompt and the interpreter will evaluate it and print the result. This is wonderful both for learning the language and for debugging or otherwise investigating code.
Lisp is dynamically typed (though statically typed flavors do exist). Most implementations of Lisp run on their own virtual machine; however, many can also be compiled to machine code. Clojure was written specifically to target the JVM; it can also target .NET and JavaScript.
Though originally created for AI research, Lisp is by no means exclusively for AI. The main reason why it's not more popular in mainstream production environments (apart from the self-perpetuating dominance of Java and C#) is library support. Common Lisp has many good libraries out there (Scheme less so), but it pales in comparison to the vast amount of library support available for Java or Python.
If you want to get started, I recommend downloading Racket, a highly popular implementation of Scheme. It has everything you need, including a simple-but-very-powerful IDE with a read-eval-print loop, right out of the box. Though originally developed as a teaching language, it comes with a very large standard library more characteristic of Common Lisp than of Scheme. As a result, it's seeing use in real production environments.
Runtime Environments
Common Lisp and Scheme generally have their own unique runtime environments. There are some variants of Scheme (Chicken and Gambit) which can be translated to C and then linked with their environments so as to be able to be deployed as stand alone executable programs. Clojure runs in the JVM, and there is also a CLR port, but its not clear to me that the CLR port is current with the JVM. Clojure also has Clojurescript, which targets a Javascript runtime.
Which is Better to Learn First
I don't think that question has a good answer. Its up to you. Although if you have experience with the JVM, Clojure might be a bit smoother to start with.
What is Better about Lisp
That's a question liable to start a flame war. I don't have much lisp experience. I started learning Clojure a few months ago in earnest, have looked at Common Lisp and Scheme on and off over the years.
What I like is their dynamic natures. You need to change a function at runtime while your program is running? No problem! Like any power tool, you have to be careful not to chop your bits off when using this.
The power and expressiveness is addicting too. I am able to do some things with little effort that I know I could not achieve in Java, or I know would require a lot more work. Specifically, I was able to put together a description of a data structure - and though the use of macros, delay evaluation of parts of the data until the right time. If I had done that in Java, I would not have been able to nest the declarations like I did because they would have evaluated in the wrong order. Pain would have ensued.
I also like Clojure's view of functional programming, although I have to say it requires work to adjust.
Is Lisp General Purpose
Yes.
--
Mark Volkman has a really good article on Clojure. Many basics are there. One thing that I did in the beginning was to just fire up a repl and experiment when I needed to figure something out programmatically. e.g. explore an API or do some calculations. After a short period of time with that I started working on more building up levels of effort, and I have a project that I'm working on right now that involves Clojure.
There isn't a bad book about Clojure that has been written. The Stuart Sierra book is being updated; and the Oreilly book is about to come out soon, so you might want to wait. The Joy of Clojure is good, but I don't think its a good starter book.
For Common Lisp, I highly recommend the Land of Lisp.
For Scheme, there are several classics including The Little Schemer and SICP.
Oh, and this: http://www.infoq.com/presentations/Are-We-There-Yet-Rich-Hickey (maybe one of the most important talks you'll ever watch), and this http://www.infoq.com/presentations/hickey-clojure (IIRC, really good intro to Clojure).
common lisp
Common Lisp is both compiled and interpreted. Deployments (in Windows) can be done by an exe with DLLs. Or by a precompiled bytecode. Or by installing a Lisp system on the target device and executing the source against it.
Common Lisp is a fully usable industrial language with an active community and libraries for many different tasks.
Lisps are generally faster for development and due to the abstraction capabilities, better at developing higher level concepts. It's hard to explain. Ruby vs. C is an example of this sort of thing. All Lisps carry this capacity IMO.
Common Lisp is a general purpose language. I don't know offhand if modern Common Lisp implementations directly support executing assembly, so it may be difficult to write drivers or use compiler-unsupported CPU instructions.
I like Common Lisp, but Clojure and Racket are not to be sneezed at either. Clojure in particular represents a very interesting track, in my opinion.
For e-books, you can get On Lisp by Graham and Gentle Introduction to Symbolic Computation. Possibly others but those are the ones I can recall.
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I'm thinking of trying to make some simple 2d games, but I've yet to choose a language. A lot of people recommend either C++ with SDL or python with pygame. I keep hearing that developement on C++ is fairly slow, and developement time with Python is fairly fast.
Anyways, could anyone elaborate on this? What exactly makes development in C++ so time consuming? The programs I've made have been Project Euler-style in that they're very short and math-based, so I have no experience in larger projects.
There are two things that are relevant between C++ and Python that will affect your time-to-develop any project including a game. There are the languages themselves and the libraries. I've played with the SDL to some extent and peeked at PyGame and for your specific instance I don't think the libraries are going to be much of a factor. So I'll focus on the languages themselves.
Python is a dynamically-typed, garbage-collected language. C++ is a statically-typed, non-garbage-collected language. What this means is that in C++ a lot of your development time will be spent managing memory and dealing with your type structure. This affords you a lot of power, but the question is do you really need it?
If you're looking to write a simple game with some basic graphics and some good gameplay, then I don't think you truly need all the power that C++ will give you. If you're looking to write something that will push the envelope, be the next A-list game, be the next MMO, fit on a console or a handheld device, then you will likely need the power that C++ affords.
The power of Python is in it's ability to allow you to focus more on the problem than having to deal with testing low-level issues such as memory allocation. I can't count how many times days of development have been wasted tracking down memory leaks in C or C++. An advantage of all high level languages.
Python is very easy to learn compared to C++,so you can be up to speed a lot quicker in doing basic programming tasks. Therefore, you'll move quicker into advanced tasks as well.
C++ has a lot of power but has many ways to shoot yourself in the foot compared to Python(not saying that can't be done in Python).
The compile/debug cycle can get old sometimes in C++ depending on what you're trying to do. Although technically speaking, everytime you run a Python script it's getting "compiled" per se, it's just a quicker cycle. A good IDE can help alleviate this is in Python by automatically checking your code for syntax errors while you type it out.
If you have some code you want to test inside a larger project, it's a hassle sometimes to isolate it for testing. Whereas a good Python interpreter such as IPython, makes it easy to test a small bit of code and see how the language behaves and paste it into a file.
Python also interfaces very well with existing C/C++ code through many numerous ways. That way if a new whizbang Python module you created is really slow, then you can soup it up in C/C++ then wrap it up with Python through ctypes, Boost::Python, or SWIG.
And most of all, Python comes with a great standard library that has a lot of stuff figured out for you. It's just a matter of putting the pieces altogether! It has a great community behind it, so if it's not in the standard library, there's a good chance someone out there has solved the problem (PyGame, Numpy, SciPy, Pyserial, PyWin, etc.) for you. You can just google it, grab it and plop the code right into your program...away you go!
I've heard these complaints before about C++, but the fact is, programming in any language with which you are unfamiliar is time consuming.
A good C++ programmer can probably crank out the app much faster than an okay Python programmer and visa versa.
I think C++ often gets a bad reputation because it allows you get much lower level - pointers, memory management, etc, and if you aren't used to thinking about such things, it can take a bit of time. If you are used to working in that environment, it can become second nature.
Unless choice of language is something imposed upon you by your company, team, client, etc. I usually recommend that folks go with the language they are most comfortable with OR most interested in learning more about. If speed is the issue you are concerned with, look at the learning curve for each language and your past experience. C++ tends to have a higher learning curve, but that too depends on the person.
Kindof a non-answer I know.
Python has some big advantages over programming languages like C++. I myself have programmed a lot with C++, C and other programming languages. Lately I am also programming in Python and I got to like it very much!
You can have a quick start with Python. Since it is rather simple to learn (at least with some programming experience and enough abstract thinking), you can have fast successes. Also the script-like behaviour makes starting easy and it is also possible, to quickly test some things in the integrated shell. This can also be good for debugging.
The whole language is packed with powerful features and it has a good and rather complete set of libraries.
There was the argument that with the "right library" you can develop as quickly with C++ as with Python. This might (partly) be, but I myself have never experienced it, because such libraries are rare. I had also a big library at hand, but still lacked many valuable features in C++. The so called "standard template library" STL makes things even worse in my opinion. It is a really powerful library. But it is also that complex, that it adds the complexity of an additional programming language to C++. I really disliked it and in a company I worked in, much worktime was lost, because the compiler was not able to give useful error-output in case of errors in the STL.
Python is different. Instead of putting the "speed of the programm" on the throne -- sacrificing all else (as C++ and especially the STL does) -- it puts "speed of development" first. The language gives you a powerful toolkit and it is accompanied by a huge library. When you need speed, you can also implement time critical things in C or C++ and call it from Python.
There is also at least one big online Game implemented in Python.
It's time consuming because in C++ you have to deal with more low-level tasks.
In Python you are free to focus on the development of the actual game instead of dealing with memory management etc.
there are many things that make c++ longer to develop in. Its lower level, has pointers, different libraries for different systems, the type system, and there are others I am sure I am missing.
It takes about the same amount of time to write the same code in pretty much all of the high level languages. The win is that in certain languages it is easier to use other peoples code. In a lot of Python/Ruby/Perl apps, you write 10% of the code and import libraries to do the other 90%. That is harder in C/C++ since the libraries have different interfaces and other incompatibilities.
C++ vs Python is a pretty personal choice. Personally I feel I lose more time with not having the C/Java class system (more run time errors/debugging time, don't have anywhere near as good auto completion, need to do more documentation and optimization) than I gain (not having to write interfaces/stub function and being able to worry less about memory managment). Other people feel the exact opposite.
In the end it probably depends on the type of game. If your processor intensive go to C++ (maybe with a scripting language if it makes sense). Otherwise use whatever language you prefer
I'd focus more on choosing a framework to build your game on than trying to pick a language. Unless the goal is to learn how games work inside and out, you're going to want to use a framework. Try out a couple, and pick the one that meets your requirements and feels nice to you.
Once you've picked the framework, the language choice becomes easy - use the language for which the framework is written.
There are many options for game frameworks in C++ - pygame works for python. There are many that work with other languages/tools as well (including .NET, Lua, etc.)
Short Answer
Yes python is faster in terms of development time. There are many case studies in real life that show this. However, you don't want to do a 3d graphics engine in Python.
Do you have any programming experience at all? If not, I would start with Python which is easier to learn, even if it is not a better tool for game development. If you decide you want to program games for living, you'll probably need to switch to C++ at some point.
Note that SDL is currently slow, because it basically doesn't use hardware acceleration.
SFML is an alternative of choice, and is available in Python too.
Why limit yourself to those two options? With C# or Java you get access to a huge collection of useful libraries plus garbage collection and (in the case of C#) JIT compiling.
Furthermore, you're saying that you're looking to do game development, but from your task description it sounds like you're also looking at coding your own engine. Is that part of the exercise? Otherwise you should definitely take a look at the available Indie engines out there - lots are cheap of not free and open source.
Needless to say, working from an existing engine is definitely faster than going from scratch :)
Some people would argue that development time is slower in C++ when compared to Python.
Wouldn't it be the case that the time you saved in developing an application (or game) in python is the time you gonna use in improving performance after its developed? and in the later part when you have least options left?
It largely depends upon the purpose for which you are going to develop the application.
If you are thinking for an enterprise application in which case it is going to be hit by millions (web-app) or an application with focus on low-footprint, faster loading into memory, faster execution, then your choice is C++.
If you are projecting your application for not being use at this level, surely Python is the choice to go for.
Maintainability is considerable, but disciplined code can overcome this.
Largely depends upon long term projections. On how serious and critical the application is going to be.
I have been learning C++ for a while now, I find it very powerful. But, the problem is the the level of abstraction is not much and I have to do memory management myself.
What are the languages that I can use which uses a higher level of abstraction.
Java, C#, Ruby, Python and JavaScript are probably the big choices before you.
Java and C# are not hugely different languages. This big difference you'll find from C++ is memory management (i.e. objects are automatically freed when they are no longer referenced). You would chose these if you were interested in desktop style applications, or keen on static typing (and you'd probably choose between them based on how you feel towards Microsoft and the Windows platform). In both cases you'll find much richer standard libraries than you'll be used to from C++.
Python and Ruby take a step away from static typing, into a world where you can call and method on any object (and fail at runtime if it's not there). That is both a blessing (a lot less boilerplate code) and a curse (the compiler can't catch those errors for you anymore). Once again, you'll find they have richer standard libraries, and are higer level again than Java / C#. Performance is the main downfall, with Python being somewhat faster than Ruby as I understand it. To choose between them, you'd probably choose Ruby if you're interesting in web development for the Ruby on Rails framework community, and otherwise go with Python.
JavaScript is even more different from C++ in that it does away with classes entirely. Objects are simply cloned from other objects and can have methods and properties added to them at runtime. Very flexible, but also very easy to make into a total mess. JavaScript is the only real choice if you're interested in running applications in a browser, which is really coming into its own as a platform. You'll find the standard libraries available rather limited if you're not doing a lot with the browser, but there are quite a few good frameworks which fill in some of the gaps.
Some other interesting, though more niche choices are
Smalltalk - More or less in the Ruby and Python camp, and significantly faster as I understand it. Be careful though _ I've seen lots of good engineers learn Smalltalk and never come back ;)
Objective-C - When C went object oriented, C++ went one way (static typing), and Objective-C went the other (dynamic typing). It's quite Smalltalk inspired, and has a good standard library if you're in Mac / iPhone land. In terms of memory management, unlike everything else I've listed, it's not garbage collected (though that's now an option on Mac OS X 10.5), but it does have a reference counting scheme which makes life significantly simpler than managing memory by hand.
Lisp - I've never learnt it myself beyond what I needed for minor Emacs hacking. As I understand it, the libraries were nice in their day, but though the language remains supremely elegant, they've fallen a little behind the times.
Haskel - If you wanted a complete break from objects and classes, Haskel and it's functional approach is an interesting way to go (or Lisp as above, or F# if you are in .Net land). Basically, you're giving up loops and variables in favour of doing everything recursively. Takes some time to wrap your mind around, and probably isn't practical for most real world applications, but it's a good one to learn.
Eiffel - I love it - Very clean syntax, and designed for serious engineering type systems. Statically types like C# and Java, and with a weaker standard library, but it will make you really think about language and class library design.
ActionScript and Flex - The programming interface to Flash, which is based on what seems to be a statically typed version of JavaScript. I've played with it a bit, and it's quite slick if you're interested in developing media based applications. You can also push beyond the browser with Flex and into the Air platform to build real desktop apps.
I would say that from your question you probably haven't finished learning about C++. If you're still doing your own memory managment then you still have a long way to go my friend!
Check out the auto_ptr and shared_ptr - check out the Boost libraries.
Similarly with abstraction - what are you specifically complaining about? AFAIK there's not much you can't do with C++ that is present in other strongly-typed languages.
I know this doesn't answer your question - you want to move forwards, but C++ is one of those things where you never really stop learning. If you get bored, take a brief foray into templates and template meta-programming...
I see a lot of excellent suggestions so far. However, I think there's something missing, assembler.
Why learn assembly language?
It's not as difficult as you may think. Assembly language is a lot smaller in scope than many modern languages, there are a few tricks you need to understand for it to make sense, but it's not that complicated.
It broadens your knowledge base. Knowing the fundamentals is almost always beneficial, even when working at a high level.
It can be extremely useful when debugging. Especially debugging native code without the source, the knowledge you gain from learning assembler enhances your ability to debug in these situations by leaps and bounds.
It gives you more options. When the rare circumstance comes up where assembly code is needed you won't be helpless.
It's good for your resume. It shows that you learn beyond just the bare minimum needed to keep your current job, it shows a curiosity about fundamentals, and it puts you in a different class of programmers, and that class tends to be more experienced and more capable.
It's just plain cool.
Some assembly language resources:
Sandpile.org (assembly language / processor architecture reference)
Gavin's Guide to 80x86 Assembly (a decent online tutorial)
Assembly Language for Intel-Based Computers (5e) (a decent textbook for x86 assembly)
Trying something really foreign like Haskell will allow you to think in different ways. It also helps you to think recursively. C++ has recursion but it infiltrates many more parts of functional languages.
ditto Lisp,.. or scheme
Even if you don't ever use it, it's handy. I only really got template programming after learning it.
Another one is prolog. it puts you in a non sequential mindset.
If you're comfortable with C++ syntax and style, you might find D to be an interesting language. Or if you want to branch out, any of Python, C#, Java, Ruby would be excellent choices.
C# if you're in the Microsoft ecosystem.
Python and Ruby seem to have the most traction in the Linux/Unix/etc space.
ObjectiveC is dominant on the Macintosh and iPhone. The most recent MacOS implements garbage collection for a subset of the frameworks, but to use the rest you'd have to do resource management yourself.
You could learn Java, as it does garbage collection as well, but the number of frameworks you'd need to become familiar with to be a productive Java developer is daunting.
Well if you're looking for a very high level of abstraction and memory management then I'd say lisp would be an ideal candidate. I'm learning it now, slowly, and it's the most fun I've had with a new language.
Having said that Python or Ruby may be a better compromise between expressiveness and popularity. Python's Django framework is one of the better RAD frameworks if you're looking for web application stuff.
I'd say it depends on the kind of programming you want to try. If you want to stay on the OOP side, learn Python or Ruby, both languages provide an easy way to create bindings to use your C++ code from a script (for efficiency reasons).
If you need another approach to programming, learn a "functional" language like Lisp or Haskell.
And if you need to include a fast and small scripting language inside your C++ application, try Lua.
Last but not least, if you know Java and hate it, you can try Scala, a language where you can mix your Java classes with your Scala code, very interesting.
Scheme.
The Little Schemer and Structure and Interpretation of Computer Program will stretch your mind in strange and wonderful ways.
DrScheme is a good IDE for beginners. The Scheme Programming Language makes a good, free reference.
try c# much :)
if you want to abstract memory management, Java comes to my mind instantly.
I suggest learning database design and a query language such as SQL.
You can start with a desktop tool like Microsoft Access or use the free SQL Server Express or Postgre or MySQL.
Well I think there is no predefined route in learning programming languages. You may learn your next lang based on your job needs, academic research, just for fun, etc. There are many options.
In you feel comfortable in C++, you can go down and learn some assembly. It's a dark art but you'll be glad when you encounter some hard debugging session.
In terms of more abstraction, Smalltalk is extremely fun, OOP-pure and 100% dynamic (debugging is a pleasant thing to do, which is not in static-typed languages). Dolphin Smalltalk is a good implementation for Windows, even the free community edition gives enough to play with. In multiplatform Smalltalk VMs, go for Visualworks or Squeak. Visualworks is extremely stable and comes with a lot of documentation.
Python is used today in many, many fields. I don't know anything about Python excepting the basic syntax and semantics, but it's required today for many jobs.
Java it's, well Java. It's interesting that Java never catch on me. You may get interested on Java, altough. Ask here for advantages of using it over C++ or other OOP languages.
For Web development go for Javascript, specially considering the AJAX wave. It's getting interesting those days. We've talked about Smalltalk, all right, Seaside is an amazing framework for web development. It works (at least I tried on) Squeak /Visualworks... it's beatiful.
Well, there are a lot of more to get your hands on: Scheme, LISP, Ruby, Lua, Bash (!), Perl (ugh), Haskell... Try them all and have fun!
Qt
Why not learn Qt? Its a great application development framework available on all platforms and even mobile devices!
Clojure is well worth exploring as it meets both of your criteria:
It has a strong emphasis on programming with higher level abstractions. see e.g. this video: Clojure: The Art of Abstraction
It has automatic memory management / garbage collection (via the JVM, which has some of the world's best GC implementations)
I'll give some examples using just one abstraction: in Clojure you can manipulate pretty much any data structure via the sequence abstraction.
;; treat a vector as a sequence and reverse it
(reverse [1 2 3 4 5])
=> (5 4 3 2 1)
;; Take 10 items from a infinite sequence
(take 10 (range))
=> (0 1 2 3 4 5 6 7 8 9)
;; Treat a String as a sequence of characters, calculate the frequencies
(frequencies "abracadabra")
=> {\a 5, \b 2, \r 2, \c 1, \d 1}
;; Define an infinite lazy sequence of fibonacci numbers, take the first 10
(def fibs (concat [0 1] (lazy-seq (map + fibs (rest fibs)))))
(take 10 fibs)
=> (0 1 1 2 3 5 8 13 21 34)
Since you are already into C++, next step would be to learn .Net through managed C++ or managed extensions for C++..this will get you a step in the big world of .Net framework..Once you understand the framework, makes it more comfortable to learn other .Net languages like C#, VB.Net etc.
One of the areas that MC++ excels in, and is in fact unique in amongst the .NET languages, is the ability to take an existing unmanaged (C++) application, recompile it with the /clr switch, have it generate MSIL and then run under the CLR. This extraordinary feat is aptly termed "It Just Works (IJW)!" There are some limitations, but for the most part, the application will just run. The C++ code can consist of old-fashioned printf statements, MFC, ATL, or even templates!
I recommend python as it's not only a sexy language, but also very widely used and easy to integrate with C++ through Boost.Python.
But as Thomi said, there's lot to explore in C++ and with the help of Boost libraries it's becoming really easy to develop in.
Rather than suggest a specific language, I would recommend you pick any language or languages that offer the following 4 features:
Automatic Memory Management
Reflection/Introspection
Declarative/Functional constructs(e.g. lambda functions)
Duck Typing
The idea here is to expand your programming perspective to include concepts that the C++ language does not offer you out of the box.
It depends on what you want to do. If you have some specific tasks that you are interested in accomplishing then look at languages that are best for those types of tasks. The best way to learn a language is to actually use it.
I'd say get started with Python. It has a higher level of abstraction and it teaches you the importance of indenting and making "pretty" code. Not that "pretty" is very important, but it will make the future maintainer of your code a lot happier :)
There's a lot of example code out there, and if you are into Linux there are various distributions out there who have all (or most) of their tools based on the language. If you like digging into how managing an operating systems works (something most programmers do) it's a good start. Before I get the flames I said managing, not the actual kernel stuff for that you mostly need C and you should have that covered.
On the other hand it might be nice to dive into the C side of things, ignore the OO stuff and learn functional programming. If you head down that road I also suggest to start with basic assembly language like one of the upper posts suggested. Maybe HLA (High-Level Assembly by Randall Hyde, he wrote a great book called Art of Assembly Language Programming) is a good start. You'll either learn to love memory management or hate it for the rest of your live. Good to know in case you want to start a career in programming :)
However if you're looking to make a job out of programming, Java and J2EE is an easy money maker if you know what you're doing. IMHO it gets boring really quick though.
Personally, I have been programming in Java, Python, C/++ and my favorite has to be python. Although C++ can do everything Python can do and more, I wrote a Python program with about 10 lines that would take about 50 in C++. So, moral of the story, use python.
If you haven't already, try out a scripting language. It should change the way you work & think. Hopefully, in a good way :)
I've got to put up a separate answer for Perl. While Python is roughly equivalent in functionality and considered more clean and modern, Perl has an elegance all of its own - the elegance of pure pragmatism. It also boasts a truly great library support. Take a look at Perl to expand your brain in the direction opposite to Haskel :) (although Perl aficionados claim that it can be used for functional programming).
Rust
Syntactically similar to C++
Designed for performance and safety, especially safe concurrency