I have a program (cpp) with many classes. Every class is in separate source file (.h + .cpp).
How can I split the compiled program into multiple files (instead of one big executable file)?
Let's say, one file for every class (same as the code structure).
So that every time there is change in a specific class, I compile only that class, and replace the specific compiled file related to that class.
(Something similar to .DLL files in Windows.)
Example from real life:
I am making TUI interface for managing mysql.
I would like to create mysql text editor (TUI) with ncurses.
the code (class) for creating and managing single window object is in
'textWin.cpp' + 'textWin.h'
the code (class) for managing multiple windows, by creating windows objects from previous class is in winMan.cpp winMan.h
the code (class) for managing mysql database is in :
mysql.cpp mysql.h
and so on...
so, I have the following files:
MyProgram.cpp
- winMan.cpp + winMan.h
- textWin.cpp + textWin.h
- mysql.cpp + mysql.h
- ..
- ..
After g++ compilation, I get one executable file, './MyProgram' (size about 15Mb.) which I deliver to all my customers (1000's of them).
I Just found a typo in textWin.cpp, I fixed it, and I told to all customers that there is an update... all of them need to download one big 15Mb file, this consumes allot of bandwidth and server resources, for just a small update.
Is there a way to send to all my customers smaller file, that contains only the compiled code for textWin class ?
I use g++ on Centos7
The gcc compiler will happily take a list of cpp files to compile together to make one executable. You don't need to write a "containing" cpp file. However, you still have the issue that each time it rebuilds them all.
The alternative is to build each sourcefile separately to an object file, then link those all together. Hopefully each of those invocations of the compiler will add up to less time than the single command-line. But how to keep track of which cpp files actually need to be rebuilt?
The usual approach is to use a makefile and a make utility which will check the dates of all the mentioned files. There are a variety of flavours of makefile, and helper makefile engines. Download a simple package like gzip and you can quickly get an idea of how the Makefile is structured. Then there is lots of help online, or you may decide that this is just too much trouble for a project with 5 files in it.
As suggested in the comments by #RSahu
Shared Libraries (.so files) is the way to split your compiled code.
here is a small example:
https://www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html
Of course, you could put your texts into separate text-files and only deploy those in the an error is there. For your special use case, where binary differences must be deployed, this question might be helpful: How do I create binary patches?
Another option, do proper versioning. That way, your customers might be able to decide for themselves. That is, if they need this update.
Related
Question
In ninja, I can compile a single C++ file by running ninja path/to/my/object.file.o.
Is there a way to achieve the same in bazel?
Use case / Background
During refactoring, in particular when changing interfaces in .hpp files, I usually want to focus on one single complex user of the interface first. I want to iterate on that one user until my refactoring works as expected on complex_user.cpp and I am happy with the new interfaces. Only afterwards, I want to adjust all other users. I hence want to get the compiler errors / warnings only from my complex_user.cpp file while ignoring all other places where .hpp might be included
Try --save_temps. bazel build --save_temps //my:library will give you the .o, .s, and similar files for only the targets listed on the command line.
--compile_one_dependency is designed for a similar use case, if you want to specify the target to build by the .cpp file instead of specifying a particular cc_library.
You need to implement a custom-made rule cc_object_file. Since the Bazel cc_rules are open source you can use this as a starting point.
I am working on an assignment where I have main.cpp,lego.cpp, and lego.h. My program currently runs fine and gives out the desired output. My issue is that to submit, I must have everything in a single cpp file. Would appreciate if someone could give a simple example. (I want everything in main.cpp)
Merge C++ files into a single source file
i found this link that is similar but I cant grasp the example
if anyone has this problem I just fixed it by doing this
class lego {things in class};
lego::functionA(){}
lego::functionB(){}
int main(){};
make sure that you delete any other cpp files that are in your source folder and remove any header files from main. Was what was causing my issue.
Combining two cpp files into one cpp file
On a POSIX system, you can use the following command:
cat main.cpp lego.cpp > combined.cpp
On windows, use type instead of cat.
This trivial approach works for most programs, and very likely for a simple assignment. But this can have problems with more complicated programs in particular those that rely heavily on pre-processor.
using the command prompt by combining the files. you need to put the files that you need to combine in a single folder and using the command line (windows + r, on windows 10) run commands that access the directory in which the files are.
Enter the command copy/b *.cpp combined.cpp That will save the two cpp files into one file combined.cpp.
Then access the combined file combined.cpp in the same directory.
This might help you too https://www.youtube.com/watch?v=0atEx7EngoE
There is a legacy code which uses 'make' to build all C++ files. I am trying to decrease the number of files being included during build, that can create some space to add in some new code.(the new code is to set up serial communication). However, these files seems to be dependent on each other and I am having a hard time figuring out which ones to exclude from the build. The format of the makefile is as follows:
$(ObjDir)\a.obj: w:\a.cpp
$(ObjDir)\b.obj: w:\b.cpp
main_obj=\
$(ObjDir)\a.obj\
$(ObjDir)\b.obj
mainEXE.exe:$(main_obj)
mainEXE.exe
mainEXE.map
There is only one file I need to tamper with while adding the new lines of code. I am trying to keep only that particular file when build happens. Is there way I could figure out the dependencies?
I'm compiling CEF (Chromium Embedded Framework) for our local html5 presentation.
I should say I'm very new for all this (CEF and C++).
I've already optimized cefclient project for the presentation, but I need to embed all html/js/css/etc files into project (reading from local storage is not an option).
As I understood, I should use .zip or .pak (renamed zip) files to embed. But how can I use them inside the project?
Should I use some lib for unzipping (zlib?) or there is another popular way? And how can I be sure that files will be compiled into project?
Sorry for such basic questions but there are very few information about this (or google hates me today).
Thank you for any help!
UPD: found great tool - WBEA (http://asterclick.drclue.net/WBEA.html), it looks like exactly what I want to, but works pretty slow (with JS).
UPD 2: It turns out that there are many ways to make HTML5 desktop application, for example Node-Webkit.
Here is an article that compares some of them http://clintberry.com/2013/html5-apps-desktop-2013/
You need:
Create zip file whitin your resources.
Embed it as win32 resource (after this step you will get correct executable with .zip file inside).
Create custom scheme handler to access this zip file.
CefZipReader class will be handly to implement handler from step 3.
Look around, may be something like what you want already exist somewhere.
This sounds very similar to self extracting installers.
No need to compile anything, just concatenate the zip to the end of the executable. All you need to do is find the offset at runtime from the start of the executable. This can be done easily by writing a large magic number and looking for it later.
Example Linux:
cat app magic_number data > new_app
Example Windows:
copy app.exe /B + magic.dat /B + data.dat /B new_app.exe
I'm beginning development on an acoustic spectrum analysis tool (inspired by spek) written in C++ with gtkmm (C++ bindings for the GTK+ GUI toolkit). I would imagine that I should know how to do this by now, however...
My directory structure is a-la-GNOME, e.g src/, data/, po/, man/. The specific situation that presented the need for my inquiry is the use of a GTK UI Manager that will be located in data/ui. For this specific situation, I want to be able to load the user-interface from this file in an install-independent manner (e.g. loading of the file does not depend on a make install; the executable may be run [and load the UI file] either from src/ after running make [thus compiling the sources into the selfsame exectuable] or from its install prefix). How would I refer to the UI file in my source code (keeping in mind that the loading of the file is not performed by creating a file object (fopen(...)) but rather by passing a file location as a string argument to (UIManager).add_ui_from_file(...))?
In addition to this particular situation of a UI file, how would I do similar references to files (i.e. databases, INI files, XML schemas) by using the autotools build process? Is there a piece of relevant Automake code to quickly set up a project to use this type of directory structure?
simply try to use both files (with the un-installed taking precedence):
if(!(UIManager).add_ui_from_file(../data/ui/mygui))
(UIManager).add_ui_from_file(/incalled/location/mygui)
In Glom, I created a helper function that tries both locations, with both locations being defined in the Makefile.am (this is simpler if you have only one Makefile.am, by using non-recursive automake, which is simpler anyway):
http://git.gnome.org/browse/glom/tree/glom/glade_utils.h#n38