c++ macros with memory?

Question

Is it possible to define macros

write_foo(A);
and
read_foo();

so that:

WRITE_FOO(hello);

code_block_1;

READ_FOO();

code         


        

Answer 1

Macros cannot redefine other macros, but you can do it manually.

#define FOO hello

FOO // expands to hello

#undef FOO
#define FOO world

FOO // expands to world

#undef FOO
#define FOO blah

FOO // expands to blah

Unfortunately, the #define + #undef combination cannot be encapsulated in any other structure that I am aware of.