Popular Python recipes tagged "switch"

Simulate C's switch statement (Python)

2016-12-11T16:28:50-08:00

Python recipe 580730 by Vasudev Ram (c, features, language, python, switch).

This recipe shows a Python construct that can behave somewhat like C's switch statement. It is not a perfect one-to-one simulation. But it does have some of the features of the C switch. One feature not supported is the fall-through feature in C's switch.

Range comparison (Python)

2012-06-06T12:00:52-07:00

Python recipe 578158 by Charlie Clark (case, comparison, switch, ternary).

Although Python now has something similar to ternary operator with the result if ... else other result construction and this allows chaining (adding additional conditions on the if side, this soon becomes unreadable. A common use case is to filter values by ranges so I wrote the following when porting some code from PHP once I found I no longer understand the logic for a simple three-way filter.

Fast and elegant switch/case-like dispatch (Python)

2011-09-02T01:49:40-07:00

Python recipe 577864 by Jan Kaliszewski (case, decorator, dispatcher, performance, switch). Revision 4.

My approach to that common issue focuses on efficiency and elegant, declarative style of definition. That's why:

The way switches work is based on unwrapped defaultdict/list lookup.
The way you define switches is based on classes and easy-to-use decorators (note that you can use subclassing in a flexible way -- without any negative impact on efficiency!).
Its use cases focus on a-lot-of-keys situations and it does not cover the fall-through feature (though you can reach its semantics if you really need that -- by calling class methods...).

Concrete Class Finder (Python)

2011-08-24T05:29:15-07:00

Python recipe 577858 by Lucio Santi (case, class, design, finder, match, oop, pattern, suitable, switch).

This recipe implements a design pattern useful for performing an object-oriented case analysis for a particular object (or a collection of objects as well). Essentially, it is an alternative to complex if-then-else or switches. Modelling each case with a particular class, the Concrete Class Finder searches for an appropriate case/class that applies to the given object/s. Once found, this class can be used in an homogeneous way, independently of the object/s previously considered.

A powerful yet simple switch-like dispatch system for Python (Python)

2010-12-21T04:38:48-08:00

Python recipe 577507 by Michael Kent (dispatcher, switch). Revision 2.

This module provides a powerful 'switch'-like dispatcher system, using decorators to give a syntax somewhat like that of the switch statement in C. Values for switch cases can be anything comparable via '==', a string for use on the left-hand side of the 'in' operator, or a regular expression. Iterables of these types can also be used.