How to create macro with git branch name?

[pajczur]

Hello,
Third time I try to figure out how can I use scripts in Projucer. And with now success. Please help me.

Now I want to have any string variable or macro that keep my git current branch.
I try to do that for 2 hours and no success.

My last try was to use that line:
GIT_NAME=echo $git branch --show-current

Inside the box “Extra Preprocessor Definitions” in Projucer.

But I get error.

For any help great thanks in advance,
Best Regards

[pajczur]

I also tried that:
${GIT_NAME =echo $git branch --show-current}

Inside box “Extra Compiler Flags”. But it also doesn’t work.

[reuk]

I don’t think there’s a way of doing this directly from the Projucer.

The simplest way is probably to use a pre-build script that generates a .cpp file containing a constant string (const char* currentGitBranchName = ...) representing the branch name, and to declare extern const char* currentGitBranchName; in one of your headers.

To avoid unnecessary rebuilds/links, your pre-build script might check the current contents of the file and avoid modifying it if the git branch hasn’t changed.

[pajczur]

Hello reuk,
great thanks for your reply.

Yes I’ve searched whole world internet
And I found many advices exactly as yours, to create with script the file containing string with branch name.

But the problem is I can’t find exactly what command should I use and exactly where in Projucer should I paste it? I can’t even find any tutorial how to write such scripts. So I don’t even know what syntax should be used.

I tired to use everything was shown here:

Include Git commit hash and/or branch name in C/C++ source

I pasted code to Projucer. But after all I always have errors. I’ve already spent about 4 hours to solve that, but still with no success.

[pajczur]

I’ve also was tying solutions showed here:

Where to write version number only once

Ideally I would like to write the version number of my project only in one place, and have it accessed/propagated throughout the whole build process, on Mac and Windows. By that, I mean that I want the version number available not only at the level of C++ code (for that, a simple #define would be enough), but also for the pre and post build scripts executed by Xcode and Visual Studio. Any ideas?

But also with no success.

Probably I use wrong syntax and in wrong place of Projucer.

[reuk]

Are you building on multiple platforms? If so, there may not be a single answer. On Windows, you’d probably need a Batch script to do it, and you might use sh or bash on macOS/Linux. Alternatively, you could ensure that your build machine has Python installed, and then use that.

This sort of thing is one reason that developers use tools like CMake. CMake is a scripting language as well as a build system, so it can be used to implement these sorts of custom behaviours.

In one project, I used the following setup to add a git hash to my builds (branch name could be achieved similarly):

git_hash.cpp.in

#include <git_hash.hpp>

char const* git::hash = "@GIT_HASH@";
char const* git::version = "@PROJECT_VERSION@";

git_hash.hpp

#pragma once

namespace git {
extern char const *hash;
extern char const *version;
} // namespace git

CMakeLists.txt

add_library(git_version_info STATIC)

find_package(Git)

# https://stackoverflow.com/a/21028226
execute_process(COMMAND
  "${GIT_EXECUTABLE}" describe --match=NeVeRmAtCh --always --abbrev=40 --dirty
  WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
  OUTPUT_VARIABLE GIT_HASH
  ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)

configure_file("${CMAKE_CURRENT_SOURCE_DIR}/git_hash.cpp.in"
    "${CMAKE_CURRENT_BINARY_DIR}/git_hash.cpp" @ONLY)

target_sources(git_version_info PRIVATE
    "${CMAKE_CURRENT_BINARY_DIR}/git_hash.cpp"
    git_hash.hpp)

target_include_directories(git_version_info PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}")

target_compile_features(git_version_info PUBLIC cxx_std_17)

set_target_properties(git_version_info PROPERTIES
    POSITION_INDEPENDENT_CODE TRUE
    VISIBILITY_INLINES_HIDDEN TRUE
    C_VISIBILITY_PRESET hidden
    CXX_VISIBILITY_PRESET hidden)

This creates a static library that just defines git and project info strings. This library can be linked into targets that require this information.

[pajczur]

Hello reuk,
great great great thanks for your detailed help.

Unfortunately it doesn’t help me. At the moment I have only VS available to test. Later I will try on my Mac in my home.

By the way it still looks very complicated for me.

While I just need to call in command line:
git branch --show-current

And then the result I need to assign to some macro like #define CURRENT_BRANCH or anything like that. So do I really need so much line of code to do do that?

Best Regards

[szemek]

I have an idea for a very naive approach. You can generate a header with a following content

echo "#define CURRENT_BRANCH \"$(git branch --show-current)\"" > branch.h

and include it

#include "branch.h"

[pajczur]

Szemek, great thanks I will test it for a moment.

I’ve already found my own script, but due to fact I don’t know the syntax, my script is much longer but probably do the same as your one line. My looks like that:

git branch --show-current >> temp_file.h
set /p branchname=<temp_file.h
set branchmacro=#define BRANCH_NAME %branchname%
echo #pragma once >> git_data.h
echo %branchmacro% >> git_data.h
del temp_file.h

But the problem is I still have no idea how to use it in Projucer, to force Projucer to launch those lines while opening project in VS from Projucer?

[pajczur]

@szemek

echo "#define CURRENT_BRANCH \"$(git branch --show-current)\"" > branch.h

Szemek, unfortunately your line of code doesn’t work. It produces branch.h file, but inside of that file I get line:
"#define CURRENT_BRANCH \"$(git branch --show-current)\""

So there is not my current branch name, there is only git command printed.
I tried to remove quotation marks, but it desn’t help.

But actually it doesn’t matter while I have my own lines which work fine. But I have no idea how to use that from Projucer.

And the second question is, why do you say it’s very naive approach? What’s wrong with that?

[pajczur]

OK finally I’ve done that.
I created myScript.bat file.

And inside that file I added those lines:

git branch --show-current >> temp_file.h
set /p branchname=<temp_file.h
set branchmacro=#define BRANCH_NAME %branchname%
echo #pragma once >> git_data.h
echo %branchmacro% >> git_data.h
del temp_file.h

And then in Projucer project settings in field “Post-Export Shell Command (Windows)” I added line:
%%1%%\myScript.bat

And finally it works as I expect. But I spent whole day to do such small thing. And still somebody say it’s naive approach. So I am really sad, but still happy I found the solution

[szemek]

I tested my one-liner in zsh shell on macOS, but command prompt or PowerShell on Windows have different interpolations - that’s why my one-liner didn’t work for you.

Answering your second question - nothing is wrong with naive approach. If it works for you, then it works for you. I’m glad that you found the solution

@pajczur

And still somebody say it’s naive approach. So I am really sad, but still happy I found the solution

Well, I wrote something different I was describing only my idea, not yours.

@szemek

I have an idea for a very naive approach.

[pajczur]

Hey great thanks for your help.

But it looks like I have another problem. Now when I have the current branch name I don’t know how to compare strings in macro defining.

I know I can use strcmp but actually it gives me result during runtime. But I want to know it in compile time.

I tried that:
#if strcmp(BRANCH_NAME, “master”) == 0
#define IS_MASTER_BRANCH 1
#else
#define IS_MASTER_BRANCH 0
#endif

But of course it doesn’t work.

[pajczur]

OK, I’ve just realised I can compare strings directly inside bat file with script.