Hi,

There is the __debug__ builtin variable which is equal to True by
default, but is equal to False when Python is run with the -O command
line option.

The compiler removes dead code when -O is used. Example:

$ cat x.py
def func():
    if __debug__: print("debug")

import dis
dis.dis(func)

# "debug" constant is checked at runtime
$ python3 x.py
  2           0 LOAD_GLOBAL              0 (print)
              2 LOAD_CONST               1 ('debug')
              4 CALL_FUNCTION            1
              6 POP_TOP
              8 LOAD_CONST               0 (None)
             10 RETURN_VALUE

# code removed by the compiler
$ python3 -O x.py
  2           0 LOAD_CONST               0 (None)
              2 RETURN_VALUE

Victor

Le mer. 21 oct. 2020 à 14:21, Marco Sulla
<marco.sulla.pyt...@gmail.com> a écrit :
>
> If not already present, do you think it's useful to add a macro that does 
> something like
>
> # ifdef Py_DEBUG
>     fprintf(stderr, "%s\n", message);
> # endif
>
> ?
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