Are nested functions a bad thing in gcc ? [closed]

Answer 1

I'm just exploring a bit different kind of use of nested functions. As an approach for 'lazy evaluation' in C.

Imagine such code:

void vars()
{
  bool b0 = code0; // do something expensive or to ugly to put into if statement
  bool b1 = code1;

  if      (b0) do_something0();
  else if (b1) do_something1();
} 

versus

void funcs()
{
  bool b0() { return code0; }
  bool b1() { return code1; }

  if      (b0()) do_something0();
  else if (b1()) do_something1();
}

This way you get clarity (well, it might be a little confusing when you see such code for the first time) while code is still executed when and only if needed. At the same time it's pretty simple to convert it back to original version.

One problem arises here if same 'value' is used multiple times. GCC was able to optimize to single 'call' when all the values are known at compile time, but I guess that wouldn't work for non trivial function calls or so. In this case 'caching' could be used, but this adds to non readability.