Metadata-Version: 1.1
Name: mprop
Version: 0.16.0
Summary: Module properties for Python
Home-page: https://github.com/josiahcarlson/mprop
Author: Josiah Carlson
Author-email: josiah.carlson@gmail.com
License: GNU LGPL v2.1
Description: 
        Description
        ===========
        
        This package intends to offer a mechanism to add properties to your modules.
        The primary use-case of this functionality is to allow for the deferred
        execution of expensive-to-compute module/package level globals without needing
        to explicitly call a function.
        
        Generally speaking, this module has two APIs that offer this functionality.
        You can use either of them or both of them, and everything will work more or
        less as you expect it to, as long as you follow the rules.
        
        Note that this package supports the use of basically any descriptor at the
        module-level, not just properties.
        
        Usage
        =====
        
        The first method of using the package supports basically any descriptor being
        used as a decorator in the standard way. We show the use of ``property`` for the
        sake of brevity::
        
            @property
            def module_property(mod):
                '''mod is the module that this property was defined in'''
        
            import mprop; mprop.init()
        
        .. warning: If you use properties or any of your own descriptors, you must
            call ``mprop.init()`` after defining all of your properties/descriptors.
            You *can* call ``mprop.init()`` multiple times if you need to add more
            properties/descriptors during runtime.
        
        Because remembering to put the import/init call at the bottom of a module can
        be annoying, we've got a special decorator that works just like the property
        object, but handles the ``mprop.init()`` call for you::
        
            from mprop import mproperty
        
            @mproperty
            def module_property2(mod):
                '''I work exactly the same as the earlier module property, but you
                don't need to make a subsequent call to ``mprop.init()``'''
        
        Regardless of which method you use, if the name of your module is ``mod`` those
        that import the module can access the properties as normal::
        
            # example.py
            from mprop import mproperty
        
            @mproperty
            def prop(mod):
                return "I was called!"
        
            def fcn():
                # I can access the property via:
                print _pmodule.prop
        
            # test.py
            import example
        
            # the below should print "I was called!"
            print example.prop
            # this should also print "I was called!"
            example.fcn()
        
        Referencing properties from within the module
        =============================================
        
        After initialization, your code may want to reference the global properties.
        If you try to access the properties directly, you will get a NameError unless
        you locally aliased the value, the initialization has not completed, or unless
        someone else injected a value with that name into the globals.
        
        If you would like to directly access properties in the module, from within the
        module, you must reference them relative to the newly generated module. This is
        available from within your functions defined in the module via ``_pmodule``,
        which is the "property-enhanced module" that offers property access.
        
        If you find it necessary to require access to the original module object
        (which doesn't support properties), you can access ``_module`` from the global
        namspace.
        
        How it works
        ============
        
        The short version: we replace the standard Python module instance in
        ``sys.modules`` during module import, which allows us to ensure that the module
        is replaced everywhere it is used. We perform some magic to ensure that
        everything available in the original module is available in the replacement
        module (the replacement module's ``__dict__`` is the module's globals), and we
        post-process everything in the module's global namespace to pull out
        descriptors as necessary.
        
        As of February 1, 2019, in order to offer proper ``@mproperty.setter/deleter``
        support, we've started initializing the module after import via the system
        profiler. More specifically, any time we get a call for ``@mproperty``, we see
        if we've installed a system profiler to clean up after this module. In CPython
        via the ``sys.setprofile()`` handler, we look for return calls from module
        creation. These auto-nest, and auto-remove themselves, so by the time your final
        mprop-using module is done initializing, our profilers are removed.
        
        We used to inject a special ``__getattribute__`` method that auto-initializes on
        first access, but it was being triggered in cases where I didn't expect.
        
        Python magic that goes on
        -------------------------
        
        * Using ``sys.getframe()`` to pull calling frame objects to get module globals
          and subsequently the module object itself
        * Replace ``sys.modules`` entries
        * Replace an instance ``__dict__``
        * Assign descriptors during runtime by modifying the base class of the
          replacement module
        * Use the system profiler to discover when a module has finished loading, to
          start initialization
        
Platform: UNKNOWN
Classifier: License :: OSI Approved :: GNU Library or Lesser General Public License (LGPL)
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.4
Classifier: Programming Language :: Python :: 2.5
Classifier: Programming Language :: Python :: 2.6
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.0
Classifier: Programming Language :: Python :: 3.1
Classifier: Programming Language :: Python :: 3.2
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
