Metadata-Version: 1.2
Name: variants
Version: 0.2.0
Summary: Library that enables the creation of alternate constructor-likevariant forms for arbitrary functions.
Home-page: https://github.com/python-variants/variants
Author: Paul Ganssle
Author-email: paul@ganssle.io
License: Apache Software License 2.0
Description: ========
        variants
        ========
        
        
        .. image:: https://img.shields.io/pypi/v/variants.svg
                :target: https://pypi.org/project/variants/
        
        .. image:: https://img.shields.io/travis/python-variants/variants.svg
                :target: https://travis-ci.org/python-variants/variants
        
        .. image:: https://readthedocs.org/projects/variants/badge/?version=latest
                :target: https://variants.readthedocs.io/en/latest/?badge=latest
                :alt: Documentation Status
        
        ``variants`` is a library that provides syntactic sugar for creating alternate forms of functions and other callables, in the same way that alternate constructors are class methods that provide alternate forms of the constructor function.
        
        To create a function with variants, simply decorate the primary form with ``@variants.primary``, which then adds the ``.variant`` decorator to the original function, which can be used to register new variants. Here is a simple example of a function that prints text, with variants that specify the source of the text to print:
        
        .. code-block:: python
        
            import variants
        
            @variants.primary
            def print_text(txt):
                print(txt)
        
            @print_text.variant('from_file')
            def print_text(fobj):
                print_text(fobj.read())
        
            @print_text.variant('from_filepath')
            def print_text(fpath):
                with open(fpath, 'r') as f:
                    print_text.from_file(f)
        
            @print_text.variant('from_url')
            def print_text(url):
                import requests
                r = requests.get(url)
                print_text(r.text)
        
        
        ``print_text`` and its variants can be used as such:
        
        .. code-block:: python
        
            print_text('Hello, world!')                 # Hello, world!
        
            # Create a text file
            with open('hello_world.txt', 'w') as f:
                f.write('Hello, world (from file)')
        
            # Print from an open file object
            with open('hello_world.txt', 'r') as f:
                print_text.from_file(f)                 # Hello, world (from file)
        
            # Print from the path to a file object
            print_text.from_filepath('hello_world.txt') # Hello, world (from file)
        
            # Print from a URL
            hw_url = 'https://ganssle.io/files/hello_world.txt'
            print_text.from_url(hw_url)                 # Hello, world! (from url)
        
        
        Differences from singledispatch
        -------------------------------
        
        While ``variants`` and |singledispatch|_ are both intended to provide alternative implementations
        to a primary function, the overall aims are slightly different. ``singledispatch`` transparently
        dispatches to variant functions based on the *type* of the argument, whereas ``variants`` provides
        *explicit* alternative forms of the function. Note that in the above example, both
        ``print_text.from_filepath`` and ``print_text.from_url`` take a string, one representing a file
        path and one representing a URL.
        
        Additionally, the ``variants`` is compatible with ``singledispatch``, so you can have the best of
        both worlds; an example that uses both:
        
        
        .. code-block:: python
        
            @variants.primary
            @singledispatch
            def add(x, y):
                return x + y
        
            @add.variant('from_list')
            @add.register(list)
            def add(x, y):
                return x + [y]
        
        Which then automatically dispatches between named variants based on type:
        
        .. code-block:: python
        
            >>> add(1, 2)
            3
            >>> add([1], 2)
            [1, 2]
        
        But also exposes the explicit variant functions:
        
        .. code-block:: python
        
            >>> add.from_list([1], 2)
            [1, 2]
            >>> add.from_list()
                  7 @add.register(list)
                  8 def add(x, y):
            ----> 9     return x + [y]
        
            TypeError: unsupported operand type(s) for +: 'int' and 'list'
        
        It is important to note that the ``variants`` decorators **must be the outer decorators**.
        
        
        Installation
        ------------
        
        To install variants, run this command in your terminal:
        
        .. code-block:: console
        
            $ pip install variants
        
        
        Requirements
        ------------
        
        This is a library for Python, with support for versions 2.7 and 3.4+.
        
        .. |singledispatch| replace:: ``singledispatch``
        .. _singledispatch: https://docs.python.org/3/library/functools.html#functools.singledispatch
        
        
        
        Version 0.2.0 (2018-05-03)
        ==========================
        
        Features
        --------
        
        - Added the ``variants.inspect`` module, which provides a public API for
          inspecting variant function groups. It currently provides two functions:
          ``is_primary`` and ``is_primary_method``. (GH #29)
        - Added python_requires to setup, indicating Python version support. (GH #34)
        
        Bugfixes
        --------
        
        - Updated MANIFEST.in to include NEWS.rst (GH #34)
        
        Improved Documentation
        ----------------------
        
        - Updated permanent redirect links in documentation. (GH #28)
        - Flattened TOC entry for changelog in documentation. (GH #32)
        - Added section for API documentation, including documentation for the inspect
          submodule. (GH #33)
        
Keywords: variants
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Natural Language :: English
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Requires-Python: >=2.7, !=3.0.*, !=3.1.*, !=3.2.*
