modules/actions/__init__.py

	__init__.py revision 51
#!/usr/bin/python
#
# CDDL HEADER START
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# The contents of this file are subject to the terms of the
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#
# Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#

"""
package containing packaging action (file type) modules

This package contains modules describing packaging actions, or file types.  The
actions are dynamically discovered, so that new modules can be placed in this
package directory and they'll just be picked up.  The current package contents
can be seen in the section "PACKAGE CONTENTS", below.

This package has one data member: "types".  This is a dictionary which maps the
action names to the classes that represent them.

This package also has one function: "fromstr", which creates an action instance
based on a str() representation of an action.
"""

import inspect
import os

# All modules in this package (all python files except __init__.py with their
# extensions stripped off).
__all__ = [
        f[:-3]
            for f in os.listdir(__path__[0])
            if f.endswith(".py") and f != "__init__.py"
]

# A dictionary of all the types in this package, mapping to the classes that
# define them.
types = {}
for modname in __all__:
        module = __import__("%s.%s" % (__name__, modname),
            globals(), locals(), [modname])

        nvlist = inspect.getmembers(module, inspect.isclass)

        # Pull the class objects out of nvlist, keeping only those that are
        # actually defined in this package.
        classes = [
                c[1]
                    for c in nvlist
                    if '.'.join(c[1].__module__.split('.')[:-1]) == __name__
        ]
        for cls in classes:
                types[cls.name] = cls

# Clean up after ourselves
del f, modname, module, nvlist, classes, c, cls

def fromstr(str):
        """Create an action instance based on a str() representation of an action.
        """
        list = str.split(' ')

        type = list[0]

        if type not in types:
                raise KeyError, "Action '%s'" % type

        # That is, if the first attribute is a hash
        if "=" not in list[1]:
                start = 2
                hash = list[1]
        else:
                start = 1

        attrs = dict(kv.split("=", 1) for kv in list[start:])

        action = types[type](**attrs)
        if "hash" in locals():
                action.hash = hash

        return action