First of all I want to point out my concern with some pseudocode (I think you'll understand better)

Assume you have a global debug flag, or class variable named "debug",

class a :
   var debug = FALSE

and you use it to enable debug methods. There are two types of usage it as I know:

first in a method :

 method a :
      if debug then call method b;

 method b :

second in the method itself:

 method a : 
       call method b;

 method b :
      if not debug exit

And I want to know, is there any File IO or stack pointer wise difference between these two approaches. Which usage is better, safer and why?