Metadata-Version: 1.1
Name: symboldict
Version: 0.2.6
Summary: A dict class to organize and lazily import symbols
Home-page: https://github.com/Gribouillis/symboldict
Author: Eric Ringeisen
Author-email: UNKNOWN
License: MIT license
Description: 
        
        Symboldict
        ==========
        
        `Package documentation <http://symboldict.readthedocs.org>`__
        
        Organize symbols and load them lazily
        
        Install symboldict
        ------------------
        python 2::
        
                
                pip install symboldict
                
        
        python 3::
        
                
                pip3 install symboldict
                
        
        Purpose
        -------
        
        The symboldict module implements a dictionary type containing symbolic
        references to python objects in the hierarchy of importable
        modules or builtins objects. Examples of symbolic references are
        ``'os.path.isdir'``, ``'telnetlib.Telnet'``, ``'complex.conjugate'`` etc.
        References to user-defined objects are equally easy.
        
        The module implements a lazy loading mechanism for these symbols, which
        means that a dictionary can contain symbols from many different modules
        without importing any of these modules until this import becomes necessary
        in user code.
        
        Symboldicts are meant to favor loose coupling between different parts
        of an application. For example three modules ``A, B, C`` may share a
        common symboldict ``sy`` instead of importing each others symbols
        directly. ``A`` and ``B`` can use method ``sy.func()`` instead of
        function ``C.func()``, thus decreasing the knowledge that each module
        possesses about other modules.
        
        Quick Start
        -----------
        
        SymbolDict objects
        ~~~~~~~~~~~~~~~~~~
        
        A ``SymbolDict``, or dictionary of symbols, is typically created by
        a statement similar to::
        
                
                >>> sy = SymbolDict(
                ...     isfile=symbol.os.path.isfile,
                ...     Telnet=symbol.telnetlib.Telnet,
                ...     conju=symbol.complex.conjugate,
                ...     eggs=symbol.spam.eggs,
                ... )
                
        
        It is a regular dictionary, which keys are arbitrary but which values
        are instances of a new type ``Symbol``::
        
                
                >>> sy
                SymbolDict({'eggs': Symbol('spam.eggs'), 'isfile': Symbol('os.path.isfile'), ...})
                >>>
                >>> isinstance(sy, dict)
                True
                
        
        The usual dictionary operations apply::
        
                
                >>> sy['isfile']
                Symbol('os.path.isfile')
                >>> sy['eggs']
                Symbol('spam.eggs')
                >>> sy['Parser'] = Symbol('argparse.ArgumentParser')
                >>> 'Telnet' in sy
                True
                
        
        Attribute access is overloaded for symboldicts.
        It supplies a lazy access to the value symbolically represented by
        the ``Symbol`` instance::
        
                >>> sy.isfile
                <function isfile at 0x7f7fd0f40050>
                >>> sy.Telnet
                <class 'telnetlib.Telnet at 0x7fbb3a518db8'>
                >>> sy.conju
                <method 'conjugate' of 'complex' objects>
                >>> sy.eggs
                Traceback (most recent call last)
                    ...
                ImportError: No module named spam
                
        
        This syntax enables user code to manipulate the ``SymbolDict``
        instance as if it was a module containing python variables
        available through qualified names. Actual modules are imported
        only when it is necessary to do so.
        
        The values of these variables can also be obtained by the following
        alternative expression,
        which handles the case where the dictionary keys are not
        character strings or where they are existing attribute names of the
        ``dict`` class (such as ``'update'`` or ``'clear'``)::
        
                >>> sy().getvalue('isfile')
                <function isfile at 0x7f7fd0f40050>
                >>> sy().getvalue('Parser')
                <class 'argparse.ArgumentParser'>
                
        
        The call syntax ``sy()`` should be stressed here. Calling a
        ``SymbolDict`` instance returns a special lightweight adapter
        having the type ``SymbolDictControl``. Direct methods cannot
        be called on symboldicts because the attribute operator is overloaded.
        
        Symbol objects
        ~~~~~~~~~~~~~~
        
        Symbol objects (used as values in ``SymbolDict`` instances) wrap a
        dot-separated path to a python object, which may exist or not, for example::
        
                
                >>> a = Symbol('wave.Error')
                >>> b = Symbol('complex.conjugate')
                >>> c = Symbol('spam.ham.eggs')
                
        
        Attribute access is overloaded to allow building other instances
        with the dot syntax::
        
                
                >>> Symbol('spam').ham.eggs
                Symbol('spam.ham.eggs')
                
        
        A special instance named ``symbol`` is defined, which
        value is ``Symbol('')``. Its path is empty, and it permits
        expressions such as::
        
                
                >>> a = symbol.wave.Error
                >>> b = symbol.complex.conjugate
                >>> c = symbol.spam.ham.eggs
                
        
        which produce the same result as above.
        
        Defining an instance does *not* trigger an attempt
        to retrieve the indicated python object by importing modules or
        accessing attributes. However, standalone ``Symbol`` instances
        have the ability to fetch this object by calling
        the ``getvalue()`` method::
        
                
                >>> a().getvalue()
                <class 'wave.Error'>
                
        
        Again, the call syntax ``a()`` enables to bypass the overloading of
        the attribute operator. It returns a special adapter having the type
        ``SymbolControl``.
        
        A method ``hasvalue()`` indicates if a value can be obtained for
        the symbol's path. Unlike ``getvalue()``, it does not raise an exception
        when there is no value::
        
                
                >>> symbol.spam.ham().hasvalue()
                False
                
        
        This method also exists for symboldicts. It may raise ``KeyError`` if
        the  key is missing in the dictionary::
        
                
                >>> sy().hasvalue('conju')
                True
                
        
        License
        -------
        
        This software is licensed under the `MIT License <http://en.wikipedia.org/wiki/MIT_License>`__
        
        © 2014 Eric Ringeisen
        
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: POSIX
Classifier: Operating System :: Microsoft :: Windows
Classifier: Operating System :: MacOS :: MacOS X
Classifier: Topic :: Software Development :: Libraries
Classifier: Topic :: Utilities
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.4
