Decorator that allows you to specify the valid types of the parameters in a function or method.
Project description
What
Decorator that allows you to specify the valid types of the parameters in a function or method.
In case of that a call don’t match the required type will fail with a TypeError exception.
Why?
There are some cases (TODO: add some examples) where you want/need to specify a specific type to use and since python does not have type checks for parameters here’s where this is useful.
All the existing solutions that I’ve found had some problem or does not have a feature that I’d like to have, so I’ve made my own.
How to use?
- First, install the RequireType package, you can do that using pip::
pip install requiretype
In your code you just need to import and use the require decorator.
Example:
from requiretype import require @require(name=str, age=(int, float, long)) def greet_person(name, age): print "Hello {0} ({1})".format(name, age) >>> greet_person("John", 42) Hello John (42) >>> greet_person("John", "Doe") [...traceback...] TypeError: Doe is not a valid type. Valid types: <type 'int'>, <type 'float'>, <type 'long'> >>> greet_person(42, 43) [...traceback...] TypeError: 42 is not a <type 'str'> type
Some notes
Here are some details about this library. Most of them was found in one or more packages that helps you to enforce/check/require types and IMO are not good things to have and motivated me to write this.
RequireType:
does not modify args or kwargs
does not move arguments from one place to another
support both args and kwargs
allows you to use all the python 2.x supported parameters usage (if not, please report a bug)
use named arguments type definition
allows you to enforce a subset of all the available arguments
raise a standard TypeError if the arguments type are wrong
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