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Simulating an unless (reverse if) statement in Python (Python recipe) by Vasudev Ram
ActiveState Code (http://code.activestate.com/recipes/580758/)

This recipe shows how to simulate an unless statement (a sort of reverse if, like Perl has), in Python. It is just for fun and as an experiment, not meant for real use, because the effect of unless can easily be got by negating the sense of the condition in an if statement.

More details and output here:

https://jugad2.blogspot.in/2017/02/perl-like-unless-reverse-if-feature-in.html

Python, 40 lines
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# unless.py v1

# A simple program to partially simulate the unless statement 
# (a sort of reverse if statement) available in languages like Perl.
# The simulation is done by a function, not by a statement.

# Author: Vasudev Ram
# Web site: https://vasudevram.github.io
# Blog: https://jugad2.blogspot.com
# Product store: https://gumroad.com

# Define the unless function.
def unless(cond, func_if_false, func_if_true):
    if not cond:
        func_if_false()
    else:
        func_if_true()

# Test it.
def foo(): print "this is foo"
def bar(): print "this is bar"

a = 1
# Read the call below as:
# Unless a % 2 == 0, call foo, else call bar
unless (a % 2 == 0, foo, bar)
# Results in foo() being called.

a = 2
# Read the call below as:
# Unless a % 2 == 0, call foo, else call bar
unless (a % 2 == 0, foo, bar)
# Results in bar() being called.

'''
Here is the output:
$ python unless.py
this is foo
this is bar
'''
Tags: features, if, perl, programming, python, trick