Remove third_party/twisted_8_1

third_party/twisted_8_1/twisted/python/hook.py

-
-# Copyright (c) 2001-2004 Twisted Matrix Laboratories.
-# See LICENSE for details.
-
-
-
-"""
-I define support for hookable instance methods.
-
-These are methods which you can register pre-call and post-call external
-functions to augment their functionality.  People familiar with more esoteric
-languages may think of these as \"method combinations\".
-
-This could be used to add optional preconditions, user-extensible callbacks
-(a-la emacs) or a thread-safety mechanism.
-
-The four exported calls are:
-
-   - L{addPre}
-   - L{addPost}
-   - L{removePre}
-   - L{removePost}
-
-All have the signature (class, methodName, callable), and the callable they
-take must always have the signature (instance, *args, **kw) unless the
-particular signature of the method they hook is known.
-
-Hooks should typically not throw exceptions, however, no effort will be made by
-this module to prevent them from doing so.  Pre-hooks will always be called,
-but post-hooks will only be called if the pre-hooks do not raise any exceptions
-(they will still be called if the main method raises an exception).  The return
-values and exception status of the main method will be propogated (assuming
-none of the hooks raise an exception).  Hooks will be executed in the order in
-which they are added.
-
-"""
-
-# System Imports
-import string
-
-### Public Interface
-
-class HookError(Exception):
-    "An error which will fire when an invariant is violated."
-
-def addPre(klass, name, func):
-    """hook.addPre(klass, name, func) -> None
-
-    Add a function to be called before the method klass.name is invoked.
-    """
-
-    _addHook(klass, name, PRE, func)
-
-def addPost(klass, name, func):
-    """hook.addPost(klass, name, func) -> None
-
-    Add a function to be called after the method klass.name is invoked.
-    """
-    _addHook(klass, name, POST, func)
-
-def removePre(klass, name, func):
-    """hook.removePre(klass, name, func) -> None
-
-    Remove a function (previously registered with addPre) so that it
-    is no longer executed before klass.name.
-    """
-
-    _removeHook(klass, name, PRE, func)
-
-def removePost(klass, name, func):
-    """hook.removePre(klass, name, func) -> None
-
-    Remove a function (previously registered with addPost) so that it
-    is no longer executed after klass.name.
-    """
-    _removeHook(klass, name, POST, func)
-
-### "Helper" functions.
-
-hooked_func = """
-
-import %(module)s
-
-def %(name)s(*args, **kw):
-    klazz = %(module)s.%(klass)s
-    for preMethod in klazz.%(preName)s:
-        preMethod(*args, **kw)
-    try:
-        return klazz.%(originalName)s(*args, **kw)
-    finally:
-        for postMethod in klazz.%(postName)s:
-            postMethod(*args, **kw)
-"""
-
-_PRE = '__hook_pre_%s_%s_%s__'
-_POST = '__hook_post_%s_%s_%s__'
-_ORIG = '__hook_orig_%s_%s_%s__'
-
-
-def _XXX(k,n,s):
-    "string manipulation garbage"
-    x = s % (string.replace(k.__module__,'.','_'), k.__name__, n)
-    return x
-
-def PRE(k,n):
-    "(private) munging to turn a method name into a pre-hook-method-name"
-    return _XXX(k,n,_PRE)
-
-def POST(k,n):
-    "(private) munging to turn a method name into a post-hook-method-name"
-    return _XXX(k,n,_POST)
-
-def ORIG(k,n):
-    "(private) munging to turn a method name into an `original' identifier"
-    return _XXX(k,n,_ORIG)
-
-
-def _addHook(klass, name, phase, func):
-    "(private) adds a hook to a method on a class"
-    _enhook(klass, name)
-
-    if not hasattr(klass, phase(klass, name)):
-        setattr(klass, phase(klass, name), [])
-
-    phaselist = getattr(klass, phase(klass, name))
-    phaselist.append(func)
-
-
-def _removeHook(klass, name, phase, func):
-    "(private) removes a hook from a method on a class"
-    phaselistname = phase(klass, name)
-    if not hasattr(klass, ORIG(klass,name)):
-        raise HookError("no hooks present!")
-
-    phaselist = getattr(klass, phase(klass, name))
-    try: phaselist.remove(func)
-    except ValueError:
-        raise HookError("hook %s not found in removal list for %s"%
-                    (name,klass))
-
-    if not getattr(klass, PRE(klass,name)) and not getattr(klass, POST(klass, name)):
-        _dehook(klass, name)
-
-def _enhook(klass, name):
-    "(private) causes a certain method name to be hooked on a class"
-    if hasattr(klass, ORIG(klass, name)):
-        return
-
-    def newfunc(*args, **kw):
-        for preMethod in getattr(klass, PRE(klass, name)):
-            preMethod(*args, **kw)
-        try:
-            return getattr(klass, ORIG(klass, name))(*args, **kw)
-        finally:
-            for postMethod in getattr(klass, POST(klass, name)):
-                postMethod(*args, **kw)
-    try:
-        newfunc.func_name = name
-    except TypeError:
-        # Older python's don't let you do this
-        pass
-
-    oldfunc = getattr(klass, name).im_func
-    setattr(klass, ORIG(klass, name), oldfunc)
-    setattr(klass, PRE(klass, name), [])
-    setattr(klass, POST(klass, name), [])
-    setattr(klass, name, newfunc)
-
-def _dehook(klass, name):
-    "(private) causes a certain method name no longer to be hooked on a class"
-
-    if not hasattr(klass, ORIG(klass, name)):
-        raise HookError("Cannot unhook!")
-    setattr(klass, name, getattr(klass, ORIG(klass,name)))
-    delattr(klass, PRE(klass,name))
-    delattr(klass, POST(klass,name))
-    delattr(klass, ORIG(klass,name))