debugging code

[Rick Ratzel]

Python defines __debug__ to True by default, and False when 
optimizations are enabled...meaning you can enable/disable code without 
having to define/undefine vars ahead of time and without having to 
change it prior to deployment.  This is how the "assert" statement 
works.  You can only set __debug__ through the use of -O or -OO.

For example, you can define a func like this:

def printDebugStmt( stmt ) :
    if __debug__ : print stmt


...and use it like this:

$ python
 >>> i=3
 >>> printDebugStmt( "Hello World...i = %s" % i )
Hello World...i = 3
 >>>

$ python -O
 >>> i=3
 >>> printDebugStmt( "Hello World...i = %s" % i )
 >>>

...just remember to "ship" your app so it runs Python with -O or -OO. 
BTW: you can use freeze.py with -O or -OO to get the same result for a 
"frozen" app.

-Rick


beliavsky at aol.com wrote:
> If I have some debugging code in a Python program (mostly print
> statements) and I want to turn it "off", two obvious methods are to
> (1) comment out the code 
> (2) set a logical 'debug' variable at the beginning and use it to
> conditionally run the debugging code.
> 
> Is there a better way? Some other languages have conditional
> compilation. (I don't know if that is better or worse). What is the
> "best" way to maintain "production" and "debugging" versions of a
> Python program at the same time, preferably in the same file?