Question

Target is to have something like:

#define sum( f1, f2 ) ( f1 + f2 )

where

sum(2,2)

is 4 in PHP. Is that somehow possible? Even better would be if I could call:

$s = 'first';
APPEND ' and second';

when append will be defined as function/method/something else which is appending to $s so after those 2 lines $s would be ‘first and second’.

Answer 1

The point of macros in C is that they are expanded at compile time.

Therefore, using the macros does not have an impact on the speed of your code, which a function doing the same would have.

Therefore, an example of usage is:

#define MYPRINTF(x) printf("MYPRINTF says : %s\n",x)
MYPRINTF("blah");

The code above will be translated by the compiler directly into:

printf("MYPRINTF says : %s\n","blah");

The whole point of it is that it is faster than defining a function, such as this one:

void myprintf(char *x)
{
  printf("myprintf says : %s\n","blah");
}

Because there is no overhead (in a function, you need to push arguments to the stack, etc).

In an interpreted language, like PHP, the above doesn’t hold, as everything is executed directly during run-time, therefore using a mechanism like C’s #define would be absolutely useless — therefore, to answer your question, simply use ordinary functions instead.