Question

I want to have more control over macros such as assertions (and some logging macros that are not directly under my control). So I decided to do something like this, expecting it to work (in case somebody is wondering, the reason it does not work is that the last undef of MY_ASSERT_COPY invalidates MY_ASSERT right before it).

#ifndef ENABLE_FULL_ERROR_ASSERTS
#define MY_ASSERT_COPY MY_ASSERT
#undef MY_ASSERT
#define MY_ASSERT
#endif

// Code for my current class, which happens to be header only

#ifndef ENABLE_FULL_ERROR_ASSERTS
#undef MY_ASSERT
#define MY_ASSERT MY_ASSERT_COPY
#undef MY_ASSERT_COPY
#endif

Now I know a few ways around it, one being to define another macro for assertions just for that file, which I can then turn off without affecting assertions in any other part of the program. I initially thought this was a really elegant solution (before I found out it did not compile) that will allow me to use MY_ASSERT everywhere and then simply turn it off for particular files.

Since the above doesn’t work, is there a workaround that will allow me to selectively kill the macro without affecting the surrounding code and without defining another substitute macro like #define MY_ASSERT_FOR_VECTORS MY_ASSERT

Answer 1

Some compilers provide #pragma push_macroand #pragma pop_macro to save and restore macro state.

Limited portability though.