[英]Defining C++ Preprocessor macros with SCons
I'm trying to define a preprocessor macro within Scons for building a larger C/C++ project. 我正在尝试在Scons中定义一个预处理器宏来构建一个更大的C / C ++项目。
One of the libraries I'm using needs ALIGN defined. 我正在使用的其中一个库需要ALIGN定义。 To be more specific, if I add 更具体地说,如果我添加
#define ALIGN(x) __attribute((aligned(x)))
to the header file of said library, it compiles fine. 对于所述库的头文件,它编译得很好。 However, I should be able to specify this at build time, as this is how the library intends on being used. 但是,我应该能够在构建时指定它,因为这是库打算如何使用。 I know in CMake, I would be able to define the macro using something like 我知道在CMake中,我可以用类似的东西来定义宏
SET(ALIGN_DECL "__attribute__((aligned(x)))")
Defining constants in Scons like this 像这样在Scons中定义常量
myEnv.Append(CPPDEFINES = ['IAMADEFINEDCONSTANT'])
works fine, but definine a macro in this way doesn't work. 工作正常,但以这种方式定义宏不起作用。 What gives? 是什么赋予了?
Edit: fixed typo 编辑:修正错字
I was able to do it on Linux with g++ as follows: 我能够在Linux上使用g ++进行如下操作:
SConscript SConscript
env = Environment()
env.Append(CPPDEFINES=['MAX(x,y)=(x>y ? x:y)'])
env.Program(target = 'main', source = 'main.cc')
main.cc main.cc
#include <iostream>
using namespace std;
int main(int argc, char **argv)
{
int a = 3;
int b = 5;
// MAX() will be defined at compile time
cout << "Max is " << MAX(a, b) << endl;
}
Compilation 汇编
$ scons
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
g++ -o main.o -c "-DMAX(x,y)=(x>y ? x:y)" main.cc
g++ -o main main.o
scons: done building targets.
Execution 执行
./main
Max is 5
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