After frequently coming across recommendation not to use leading and double underscores in C/C++ identifiers I decided to fix all our sources once and for all. What I need to do now is convert _Identifier to Identifier_.
Should I use a specialized tool for this task of regular expressions will do for this job? In latter case what is the pattern to match C/C++ identifier?
Although I am one of those that frequently points out that names with leading underscores may be reserved, I strongly recommend you don't do this unless you are experiencing problems caused by the names. Making this global change will make your version control system less useful than it might otherwise be by causing all sorts of spurious diffs. Also, there is a chance of creating duplicate names.
Also, there are many underscore prefixed names that re perfectly valid. One thinks immediately of __LINE__ and __FILE__ etc, and of all the names of non-standard functions that may be provided by
your specific implementation. Filtering out those names will be far from trivial (I would say next to impossible), certainly a simple Perl or sed script will not be enough.
So instead, I would encourage you to change the names on a file by file basis as you make other changes to the code. Change your programming standards to avoid the leading underscore names and write new code in accordance with the standards.
If you use Visual Studio, there are refactoring plugins such as Visual Assist X to help you with this.
Perl should do the job, but there's Coccinelle for when it gets tricky.
Netbeans can do this for the whole project, using the Refactor->Rename menu command. But it only works for a single identifier a time, so you'll need to reiterate for every identifier you need to change.
If your regression tests are solid, then you should have no problems if you just write a quick perl script to replace everything and run the test suite. If you don't have solid regression tests...well, then you can do the perl script replacement and just rebuild the code. If the compilation works, then chances are pretty good that everything is fine. In other words, try the quick solution, and only use a specialized tool if that doesn't work.
Related
I have a couple of simple C++ homeworks and I know the students shared code. These are smart students and they know how to cheat moss. I'm looking for a tool that can rename variables based on their types (first variable of type int will be int1, first int array will be intptr1...), or does something similar that I cannot think of now. Do you know a quick way to do this?
edit: I'm required to use moss and report 90% match
Thanks
Yep, the tool you're looking for is called a compiler. :)
Seriously, if the programs submitted are exactly the same except for the identifier names, compiling then (without debugging info) should result in exactly the same output.
If you do this with debugging turned on, the compiler may leave meta-data in the executable that is different for each executable, hence the comment about ensuring it is off. This is also why this wont work for Java programs - that kind of info is present whether in debug mode or not (for the purposes of dynamic introspection).
EDIT: I see from the comments added to the question that you're observing some submissions that are different in more than just identifier names. If the programs are still structurally equivalent, this should still work.
EDIT: Given that the use of moss is a requirement, this probably isn't the way to go. I does seem though that moss has some support for comparing assembly - perhaps compiling to assembler and submitting that to moss is an option (depending on what compiler you're using).
You can download and try our C CloneDR duplicate code detector. It finds duplicated code even when the variable names have been changed. Multiple changes in the same chunk are treated as just one; if they rename the varaibles consistenly everywhere, you'll get back a report of "one clone" with the precise variable subsitution.
You can try Copy Paste Detector with ignoreIdentifiers turned on. You can at least use it for a first pass before going to the effort of normalizing names for moss. Or, since the source is available, maybe you can get it to spit out its internal normalization of the code.
Another way of doing this would be to compile the applications and compare their binaries, so your examination is not limited to variable/function name changing.
An HEX editor can help you with that. I just tried ExamDiff (not free $) and I was happy with the result.
So I've been working on a relatively large project by myself, and I've come to realise that some of the variable names earlier on were.. less than ideal.
But how does one change variable names in a project easily? Is there such a tool that can go through a project directory, parse all the files, and then replace the variable names to the desired one? It has to be smart enough to understand the language I imagine.
I was thinking of using regexp (sed/awk on linux?) tools to just replace the variable name, but there were many times where my particular variable is also included as a part of strings.
There's also the issue about changing stuff on a c++ namespace, because there is actually two classes in my project that share the same name, but are in different namespaces.
I remember visual studio being able to do this, but what's the safest and most elegant way to do this on linux?
It's called refactoring, but I don't remember if there's a great way to do it in C++ -- I think maybe Eclipse C++ had it; might be worth taking a look.
Safest (non automated way) way:
Make sure all your unit tests work.
Save everything into source control.
Globally replace var with XXXvarXXX (seriously)
a. Or maybe just the files you think need editing.
Try and compile. Everything that does not compile is easy to undo just remove the XXX.
When it compiles run the unit tests.
When the unit tests work. Do a global replace of XXXvarXXX to the new name.
Make sure the unit tests still work
Save everything in source control.
Tongue only half in cheek. :-)
I remember visual stuio being able to do this, but what's the safest and most elegant way to do this on linux?
You can do pretty much what you used to do in visual studio in Eclipse using the re-factoring tools, which is available for Linux.
$400 a f'n copy, but here you go: http://www.xref.sk/xrefactory/download.html
I've of course never used it.
I know C# and visual studio has a great variable changer, but does it work through all the documents im not sure. I know when you change a variable in C# it pops up in the beside the Variable text. Change All
However you may be stuck with the only option. Change variables and see where the compiler goes wrong. However its not ideal, but may be your only choice
use private variables, rename the variable and the obvious uses, correct the compiler errors.
I have a codebase that is touched by many people. While most people make an effort to keep the code nicely formatted (e.g. consistent indentation and use of braces), some don't, and even those that do can't always do it because we all use different editors, so settings like spaces vs. tabs are different.
Is there any standard lint tool that checks that code is properly formatted, but doesn't actually change it (like indent but that returns only errors and warnings)?
While this question could be answered generally, my focus is on C and C++, because that's what this project is written in.
Google uses cpplint. This is their style guide.
The Linux kernel uses a tool that does exactly this - it's called checkpatch. You'd have to modify it to check your coding standards rather than theirs, but it could be a good basis to work from. (It is also designed for C code rather than C++).
Take a look at Vera++, it has a number of rules already available but the nice part is that you can modify them or write your own.
There are several programs that can do formatting for you automatically on save (such as Eclipse). You can have format settings that everyone can use ensuring the same formatting.
It is also possible to automatically apply such formatting when code is committed. When you use SVN, the system to do this is called svn hooks. This basically starts a program to process (or check and deny) the formatting when a commit happens.
This site explains how you can make your own. But also ones already exist to do this.
What packages do you use to handle command line options, settings and config files?
I'm looking for something that reads user-defined options from the command line and/or from config files.
The options (settings) should be dividable into different groups, so that I can pass different (subsets of) options to different objects in my code.
I know of boost::program_options, but I can't quite get used to the API. Are there light-weight alternatives?
(BTW, do you ever use a global options object in your code that can be read from anywhere? Or would you consider that evil?)
At Google, we use gflags. It doesn't do configuration files, but for flags, it's a lot less painful than using getopt.
#include <gflags/gflags.h>
DEFINE_string(server, "foo", "What server to connect to");
int main(int argc, char* argv[]) {
google::ParseCommandLineFlags(&argc, &argv, true);
if (!server.empty()) {
Connect(server);
}
}
You put the DEFINE_foo at the top of the file that needs to know the value of the flag. If other files also need to know the value, you use DECLARE_foo in them. There's also pretty good support for testing, so unit tests can set different flags independently.
For command lines and C++, I've been a fan of TCLAP: Templatized Command Line Argument Parser.
http://sourceforge.net/projects/tclap/
Well, you're not going to like my answer. I use boost::program_options. The interface takes some getting used to, but once you have it down, it's amazing. Just make sure to do boatloads of unit testing, because if you get the syntax wrong you will get runtime errors.
And, yes, I store them in a singleton object (read-only). I don't think it's evil in that case. It's one of the few cases I can think of where a singleton is acceptable.
If Boost is overkill for you, GNU Gengetopt is probably, too, but IMHO, it's a fun tool to mess around with.
And, I try to stay away from global options objects, I prefer to have each class read its own config. Besides the whole "Globals are evil" philosophy, it tends to end up becoming an ever-growing mess to have all of your configuration in one place, and also it's harder to tell what configuration variables are being used where. If you keep the configuration closer to where it's being used, it's more obvious what each one is for, and easier to keep clean.
(As to what I use, personally, for everything recently it's been a proprietary command line parsing library that somebody else at my company wrote, but that doesn't help you much, unfortunately)
I've been using TCLAP for a year or two now, but randomly I stumbled across ezOptionParser. ezOptionParser doesn't suffer from "it shouldn't have to be this complex"-syndrome the same way that other option parsers do.
I'm pretty impressed so far and I'll likely be using it going forward, specifically because it supports config files. TCLAP is a more sophisticated library, but the simplicity and extra features from ezOptionParser is very compelling.
Other perks from its website include (as of 0.2.0):
Pretty printing of parsed inputs for debugging.
Auto usage message creation in three layouts (aligned, interleaved or staggered).
Single header file implementation.
Dependent only on STL.
Arbitrary short and long option names (dash '-' or plus '+' prefixes not required).
Arbitrary argument list delimiters.
Multiple flag instances allowed.
Validation of required options, number of expected arguments per flag, datatype ranges, user defined ranges, membership in lists and case for string lists.
Validation criteria definable by strings or constants.
Multiple file import with comments.
Exports to file, either set options or all options including defaults when available.
Option parse index for order dependent contexts.
GNU getopt is pretty nice. If you want a C++ feel, consider getoptpp which is a wrapper around the native getopt.
As far as configuration file is concerned, you should try to make it as stupid as possible so that parsing is easy. If you are bit considerate, you might want to use yaac&lex but that would be really a big bucks for small apps.
I also would like to suggest that you should support both config files and command line options in your application. Config files are better for those options which are to be changed less frequently. Command-line options are good when you want to pass the immediate changing arguments (typically when you are creating a app, which would be called by some other program.)
If you are working with Visual Studio 2005 on x86 and x64 Windows there is some good Command Line Parsing utilities in the SimpleLibPlus library. I have used it and found it very useful.
Not sure about command line argument parsing. I have not needed very rich capabilities in that area and have generally rolled my own to save adding more dependencies to my software. Depending upon what your needs are you may or may not want to try this route. The C++ programs I have written are generally not invoked from the command line.
On the other hand, for a config file you really can't beat an XML based format. It's readable, extensible, structured, etc... :) Plus there are lots of XML parsers out there. Despite the fact it is a C library, I tend to use libxml2 from xmlsoft.org.
Try Apache Ant. Its primary usage is Java projects, but there isn't anything Java about it, and its usable for almost anything.
Usage is fairly simple and you've got a lot of community support too. It's really good at doing things the way you're asking.
As for global options in code, I think they're quite necessary and useful. Don't misuse them, though.
Many times when I am watching others code I just want to find where and how a variable is defined. Normally what I do now is look for the type of the variable until I find the definition, that is very time consuming. And I guess that there are some tools that can help me in this rutinary situation. Any suggestion in some tools or commands to help me in this task?.
I know that using a GUI and creating a project this is done automatically I am talking of a way to do this without a GUI. I am working with only text mode. I am running under Linux and I am using C/C++, but suggestions for other languages are welcome.
Thanks a lot.
A possible solution
Michel in one of his comments propose a simple an effective solution define again the variable, in that case in compilation time, the compiler will inform where is the previous definiton. Of course to apply this solution we need to think previously in the locality of the variable.
You've already given the most appropriate tool: an IDE. This is exactly the kind of thing which an IDE excels at. Why would you not want to use an IDE if you're finding development painful without one?
Note that Emacs, Vim etc can work as IDEs - I'm not talking about forcing you the world of GUIs if you want to stay in a text-only situation, e.g. because you're SSHing in.
(I'm really not trying to be rude here. I just think you've discounted the obvious solution without explaining why.)
Edit: OK, you say you're using C++. I'm editing my response. I would use the C preprocessor and then grep for the variable. It will appear in the first place.
cpp -I...(preprocessor options here) file.cpp | grep variable
The C preprocessor will join all the includes that the program uses, and the definition has to be before any usage of that variable in the file. Not a perfect thing, but without an IDE or a complete language description/managing tool, you only have the text.
Another option would be using ctags. It understands the C and C++ syntaxes (among others), and can be searched for variables and functions using command line tools, emacs and vi, among others.
I use cscope and ctags-exuberant religiously. Run it once on my code base and then in Vim, I can use various commands like ^] or [D or [I or similar to find any definitions or declarations for a given word.
This is similar to facilities provided by mega-IDEs like Visual Studio and Eclipse.
Cscope also functions as a stand-alone tool that performs these searches.
I use one of three methods:
I will use CTags to process my source tree (nightly) and then can easily use commands in Vim (or other editors) to jump right to the definition.
I will just use grep (linux) or findstr (windows) to look for all occurrences of the variable name or type. The definition is usually quite obvious.
In Vim, you can just search backward in the scope and often find what you are looking for.
Grep for common patterns for variable declarations. Example: *, &, > or an alphanumeric followed by one or more whitespace characters then the name of the variable. Or variable name followed by zero or more whitespace characters, then a left parenthesis or a semicolon. Unless it was defined under really weird circumstances (like with some kind of macro), it works every time.
In VIM you can use gd to see local variable declarations or gD to see global variable declarations, if they're defined in the current file. Reference Go_to_definition_using_g
You can also use [i to see the definition without jumping to it, or [I to see all occurrences of the variable in all the included files as well, which will naturally show the definition as well.
If you work in Microsoft Visual Studio (which I think you could use for C++ as well, but would require working on a Windows workstation) there's an easily accessible right-click menu option for "Go to Definition...", which will take you to the definition of any currently marked variable, type or method.
if you insist on staying text mode, you can do this with either emacs or vi with the appropriate plug-ins.
But really, move into the 21st century.
EDIT: You commented that you are doing this over SSH because you need the build speed of the remote server cluster.
In that case, mount the drive on your local machine and use an IDE, and just SSH in to kick off a build.