Popular Python recipes tagged "type"

Auto assign self attributes in init using PEP 484 (Python)

2017-04-26T17:26:29-07:00

Python recipe 580790 by Ryan Gonzalez (annotations, class, self, type). Revision 2.

TL;DR: Short way of doing stuff like def __init__(self, a, b): self.a = a; self.b = b, using type annotations from PEP 484, inspired by Dart's MyConstructor(this.a, this.b) and Ruby's/Crystal's/(Moon|Coffee)Script's constructor/initialize(@a, @b).

Number of bits needed to store an integer, and its binary representation (Python)

2017-03-12T23:10:48-07:00

Python recipe 580762 by Vasudev Ram (binary, formats, integers, numbers, representation, type).

This recipe shows how to find, via Python code, the number of bits needed to store an integer, and how to generate its binary representation. It does this for integers from 0 to 256.

More details and full output here:

https://jugad2.blogspot.in/2017/03/find-number-of-bits-needed-to-store.html

Get names and types of all attributes of a Python module (Python)

2016-10-06T17:21:42-07:00

Python recipe 580705 by Vasudev Ram (documentation, introspection, modules, reflection, type).

This recipe shows how to get the names and types of all the attributes of a Python module. This can be useful when exploring new modules (either built-in or third-party), because attributes are mostly a) data elements or b) functions or methods, and for either of those, you would like to know the type of the attribute, so that, if it is a data element, you can print it, and if it is a function or method, you can print its docstring to get brief help on its arguments, processsing and outputs or return values, as a way of learning how to use it.

The code for the recipe includes an example call to it, at the end of the code. Note that you first have to import the modules that you want to introspect in this way.

Finding the sizes of various Python data types (Python)

2016-04-28T18:28:59-07:00

Python recipe 580655 by Vasudev Ram (data, datastructures, memory, python, python2, system, type).

This recipe shows how to find the sizes of various common data types in Python, both built-in and user-defined. It uses the sys.getsizeof() function and also discusses a few other points of interest.

Type checking using Python 3.x annotations (Python)

2013-05-23T22:46:19-07:00

Python recipe 578528 by David Mertz (annotations, check, decorator, python3, type, typecheck). Revision 5.

Some other recipes have been suggested to allow type checking by various means. Some of these require the use of type specification in a decorator itself. Others try to be much more elaborate in processing a large variety of annotations (but hence require much more and more convoluted code).

The recipe provided below is very short, and simply provides actual type checking of arguments and return values. It utilizes an unadorned decorator, rather than manufacture one that is parameterized by types or other arguments.

type Checking in Python using decorators (version 2.0) (Python)

2012-11-19T13:15:35-08:00

Python recipe 578330 by LL Snark (checking, debugging, decorators, type). Revision 2.

The two decorators checkparams and checkreturn allow you to check (at execution time) that function parameters or a function return value are the right type.

Method signature type checking decorator for Python 3.0 (Python)

2010-07-10T00:40:54-07:00

Python recipe 577299 by andrew johnson (checking, decorator, method, signature, type).

Clean lightweight type-checking with Python 3.0 annotations.

typesafe records (Python)

2010-07-10T01:43:38-07:00

Python recipe 577249 by andrew johnson (namedtuple, record, type, typesafe). Revision 4.

A typesafe wrapper for namedtuple.

Find all subclasses of a given class (Python)

2009-11-04T20:26:08-08:00

Python recipe 576949 by Gabriel Genellina (class, extending, inheritance, plugin, subclass, subclasses, type). Revision 3.

itersubclasses(cls) returns a generator over all subclasses of cls, in depth first order. cls must be a new-style class; old-style classes are not supported.

Type-Checking Function Overloading Decorator (Python)

2010-04-11T11:16:48-07:00

Python recipe 577065 by Ryan Lie (checkng, decorator, function, overloading, python, type). Revision 2.

The recipe presents a function overloading decorator in python that do type check. The type signature is marked with the @takes and @returns decorator, which causes the function to raise an InputParameterError exception if called with inappropriate arguments. The @overloaded function searches for the first overloads that doesn't raise TypeError or InputParameterError when called. Alternative overloads are added to the overloads list by using the @func.overload_with decorator. The order of function definition determines which function gets tried first and once it founds a compatible function, it skips the rest of the overloads list.

Homogeneous list (Python)

2009-04-14T12:09:19-07:00

Python recipe 576718 by marlonamor (list, type).

This is a little code for making a list that can have only items from a list of types

Method signature type checking decorator for Python 3 (Python)

2015-05-15T09:25:08-07:00

Python recipe 572161 by Dmitry Dvoinikov (checking, decorator, interface, method, signature, sysadmin, type). Revision 8.

This recipe allows nice and clean validation for method parameters/return values. It uses function annotations available in Python 3 for the actual signature specification.