The with statement allows all sorts of syntactic sugar in python. This snippet defines two contexts: inevitably and preferably which register a function call to be executed at the end of a block of statement. Although they are not very useful (the function call could be written directly at the end of the block, or with the help of a try...finally structure), some programmers may appreciate this style in certain circumstances.

Edited 6 Years Ago by Gribouillis: n/a

# Copyright(C) 2010 Gribouillis, member of www.daniweb.com
# licence: public domain
# tested with python 2.6 and 3.1

from __future__ import print_function
from contextlib import contextmanager

@contextmanager
def preferably(func, *args, **kwd):
    """Context to call a function in the end of a block of statement.
    func(*args, **kwd) will be called when the blocks exit unless
    the block raised an uncaugth exception."""
    yield
    func(*args, **kwd)
    
@contextmanager
def inevitably(func, *args, **kwd):
    """Context to call a function in the end of a block of statement.
    func(*args, **kwd) will be called when the block exits
    even if the block raised an uncaught exception."""
    try:
        yield
    finally:
        func(*args, **kwd)

# EXAMPLE USE

if __name__ == "__main__":
    import sys
    if sys.version_info < (3,):
        input = raw_input
        
    with preferably(print, "thank you for running this program."):
        # when this block exit, the above print will occur.
        name = input("please enter your name: ")
        print("hello", name, "!", "your named reversed is '%s'" % name[::-1] ,end=" ")
        input("<enter to continue>")
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