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# -*- test-case-name: twisted.test.test_reflect -*-
# Copyright (c) 2001-2010 Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Standardized versions of various cool and/or strange things that you can do
with Python's reflection capabilities.
"""
import sys
import os
import types
import pickle
import traceback
import weakref
import re
import warnings
import new
try:
from collections import deque
except ImportError:
deque = list
RegexType = type(re.compile(""))
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
from twisted.python.util import unsignedID
from twisted.python.deprecate import deprecated
from twisted.python.deprecate import _fullyQualifiedName as fullyQualifiedName
from twisted.python.versions import Version
class Settable:
"""
A mixin class for syntactic sugar. Lets you assign attributes by
calling with keyword arguments; for example, C{x(a=b,c=d,y=z)} is the
same as C{x.a=b;x.c=d;x.y=z}. The most useful place for this is
where you don't want to name a variable, but you do want to set
some attributes; for example, C{X()(y=z,a=b)}.
"""
def __init__(self, **kw):
self(**kw)
def __call__(self,**kw):
for key,val in kw.items():
setattr(self,key,val)
return self
class AccessorType(type):
"""Metaclass that generates properties automatically.
This is for Python 2.2 and up.
Using this metaclass for your class will give you explicit accessor
methods; a method called set_foo, will automatically create a property
'foo' that uses set_foo as a setter method. Same for get_foo and del_foo.
Note that this will only work on methods that are present on class
creation. If you add methods after the class is defined they will not
automatically become properties. Likewise, class attributes will only
be used if they are present upon class creation, and no getter function
was set - if a getter is present, the class attribute will be ignored.
This is a 2.2-only alternative to the Accessor mixin - just set in your
class definition::
__metaclass__ = AccessorType
"""
def __init__(self, name, bases, d):
type.__init__(self, name, bases, d)
accessors = {}
prefixs = ["get_", "set_", "del_"]
for k in d.keys():
v = getattr(self, k)
for i in range(3):
if k.startswith(prefixs[i]):
accessors.setdefault(k[4:], [None, None, None])[i] = v
for name, (getter, setter, deler) in accessors.items():
# create default behaviours for the property - if we leave
# the getter as None we won't be able to getattr, etc..
if getter is None:
if hasattr(self, name):
value = getattr(self, name)
def getter(this, value=value, name=name):
if name in this.__dict__:
return this.__dict__[name]
else:
return value
else:
def getter(this, name=name):
if name in this.__dict__:
return this.__dict__[name]
else:
raise AttributeError("no such attribute %r" % name)
if setter is None:
def setter(this, value, name=name):
this.__dict__[name] = value
if deler is None:
def deler(this, name=name):
del this.__dict__[name]
setattr(self, name, property(getter, setter, deler, ""))
class PropertyAccessor(object):
"""A mixin class for Python 2.2 that uses AccessorType.
This provides compatability with the pre-2.2 Accessor mixin, up
to a point.
Extending this class will give you explicit accessor methods; a
method called set_foo, for example, is the same as an if statement
in __setattr__ looking for 'foo'. Same for get_foo and del_foo.
There are also reallyDel and reallySet methods, so you can
override specifics in subclasses without clobbering __setattr__
and __getattr__, or using non-2.1 compatible code.
There is are incompatibilities with Accessor - accessor
methods added after class creation will *not* be detected. OTOH,
this method is probably way faster.
In addition, class attributes will only be used if no getter
was defined, and instance attributes will not override getter methods
whereas in original Accessor the class attribute or instance attribute
would override the getter method.
"""
# addendum to above:
# The behaviour of Accessor is wrong IMHO, and I've found bugs
# caused by it.
# -- itamar
__metaclass__ = AccessorType
def reallySet(self, k, v):
self.__dict__[k] = v
def reallyDel(self, k):
del self.__dict__[k]
class Accessor:
"""
Extending this class will give you explicit accessor methods; a
method called C{set_foo}, for example, is the same as an if statement
in L{__setattr__} looking for C{'foo'}. Same for C{get_foo} and
C{del_foo}. There are also L{reallyDel} and L{reallySet} methods,
so you can override specifics in subclasses without clobbering
L{__setattr__} and L{__getattr__}.
This implementation is for Python 2.1.
"""
def __setattr__(self, k,v):
kstring='set_%s'%k
if hasattr(self.__class__,kstring):
return getattr(self,kstring)(v)
else:
self.reallySet(k,v)
def __getattr__(self, k):
kstring='get_%s'%k
if hasattr(self.__class__,kstring):
return getattr(self,kstring)()
raise AttributeError("%s instance has no accessor for: %s" % (qual(self.__class__),k))
def __delattr__(self, k):
kstring='del_%s'%k
if hasattr(self.__class__,kstring):
getattr(self,kstring)()
return
self.reallyDel(k)
def reallySet(self, k,v):
"""
*actually* set self.k to v without incurring side-effects.
This is a hook to be overridden by subclasses.
"""
if k == "__dict__":
self.__dict__.clear()
self.__dict__.update(v)
else:
self.__dict__[k]=v
def reallyDel(self, k):
"""
*actually* del self.k without incurring side-effects. This is a
hook to be overridden by subclasses.
"""
del self.__dict__[k]
# just in case
OriginalAccessor = Accessor
class Summer(Accessor):
"""
Extend from this class to get the capability to maintain 'related
sums'. Have a tuple in your class like the following::
sums=(('amount','credit','credit_total'),
('amount','debit','debit_total'))
and the 'credit_total' member of the 'credit' member of self will
always be incremented when the 'amount' member of self is
incremented, similiarly for the debit versions.
"""
def reallySet(self, k,v):
"This method does the work."
for sum in self.sums:
attr=sum[0]
obj=sum[1]
objattr=sum[2]
if k == attr:
try:
oldval=getattr(self, attr)
except:
oldval=0
diff=v-oldval
if hasattr(self, obj):
ob=getattr(self,obj)
if ob is not None:
try:oldobjval=getattr(ob, objattr)
except:oldobjval=0.0
setattr(ob,objattr,oldobjval+diff)
elif k == obj:
if hasattr(self, attr):
x=getattr(self,attr)
setattr(self,attr,0)
y=getattr(self,k)
Accessor.reallySet(self,k,v)
setattr(self,attr,x)
Accessor.reallySet(self,y,v)
Accessor.reallySet(self,k,v)
class QueueMethod:
""" I represent a method that doesn't exist yet."""
def __init__(self, name, calls):
self.name = name
self.calls = calls
def __call__(self, *args):
self.calls.append((self.name, args))
def funcinfo(function):
"""
this is more documentation for myself than useful code.
"""
warnings.warn(
"[v2.5] Use inspect.getargspec instead of twisted.python.reflect.funcinfo",
DeprecationWarning,
stacklevel=2)
code=function.func_code
name=function.func_name
argc=code.co_argcount
argv=code.co_varnames[:argc]
defaults=function.func_defaults
out = []
out.append('The function %s accepts %s arguments' % (name ,argc))
if defaults:
required=argc-len(defaults)
out.append('It requires %s arguments' % required)
out.append('The arguments required are: %s' % argv[:required])
out.append('additional arguments are:')
for i in range(argc-required):
j=i+required
out.append('%s which has a default of' % (argv[j], defaults[i]))
return out
ISNT=0
WAS=1
IS=2
def fullFuncName(func):
qualName = (str(pickle.whichmodule(func, func.__name__)) + '.' + func.__name__)
if namedObject(qualName) is not func:
raise Exception("Couldn't find %s as %s." % (func, qualName))
return qualName
def qual(clazz):
"""Return full import path of a class."""
return clazz.__module__ + '.' + clazz.__name__
def getcurrent(clazz):
assert type(clazz) == types.ClassType, 'must be a class...'
module = namedModule(clazz.__module__)
currclass = getattr(module, clazz.__name__, None)
if currclass is None:
return clazz
return currclass
def getClass(obj):
"""Return the class or type of object 'obj'.
Returns sensible result for oldstyle and newstyle instances and types."""
if hasattr(obj, '__class__'):
return obj.__class__
else:
return type(obj)
# class graph nonsense
# I should really have a better name for this...
def isinst(inst,clazz):
if type(inst) != types.InstanceType or type(clazz)!= types.ClassType:
return isinstance(inst,clazz)
cl = inst.__class__
cl2 = getcurrent(cl)
clazz = getcurrent(clazz)
if issubclass(cl2,clazz):
if cl == cl2:
return WAS
else:
inst.__class__ = cl2
return IS
else:
return ISNT
def namedModule(name):
"""Return a module given its name."""
topLevel = __import__(name)
packages = name.split(".")[1:]
m = topLevel
for p in packages:
m = getattr(m, p)
return m
def namedObject(name):
"""Get a fully named module-global object.
"""
classSplit = name.split('.')
module = namedModule('.'.join(classSplit[:-1]))
return getattr(module, classSplit[-1])
namedClass = namedObject # backwards compat
class _NoModuleFound(Exception):
"""
No module was found because none exists.
"""
class InvalidName(ValueError):
"""
The given name is not a dot-separated list of Python objects.
"""
class ModuleNotFound(InvalidName):
"""
The module associated with the given name doesn't exist and it can't be
imported.
"""
class ObjectNotFound(InvalidName):
"""
The object associated with the given name doesn't exist and it can't be
imported.
"""
def _importAndCheckStack(importName):
"""
Import the given name as a module, then walk the stack to determine whether
the failure was the module not existing, or some code in the module (for
example a dependent import) failing. This can be helpful to determine
whether any actual application code was run. For example, to distiguish
administrative error (entering the wrong module name), from programmer
error (writing buggy code in a module that fails to import).
@raise Exception: if something bad happens. This can be any type of
exception, since nobody knows what loading some arbitrary code might do.
@raise _NoModuleFound: if no module was found.
"""
try:
try:
return __import__(importName)
except ImportError:
excType, excValue, excTraceback = sys.exc_info()
while excTraceback:
execName = excTraceback.tb_frame.f_globals["__name__"]
if (execName is None or # python 2.4+, post-cleanup
execName == importName): # python 2.3, no cleanup
raise excType, excValue, excTraceback
excTraceback = excTraceback.tb_next
raise _NoModuleFound()
except:
# Necessary for cleaning up modules in 2.3.
sys.modules.pop(importName, None)
raise
def namedAny(name):
"""
Retrieve a Python object by its fully qualified name from the global Python
module namespace. The first part of the name, that describes a module,
will be discovered and imported. Each subsequent part of the name is
treated as the name of an attribute of the object specified by all of the
name which came before it. For example, the fully-qualified name of this
object is 'twisted.python.reflect.namedAny'.
@type name: L{str}
@param name: The name of the object to return.
@raise InvalidName: If the name is an empty string, starts or ends with
a '.', or is otherwise syntactically incorrect.
@raise ModuleNotFound: If the name is syntactically correct but the
module it specifies cannot be imported because it does not appear to
exist.
@raise ObjectNotFound: If the name is syntactically correct, includes at
least one '.', but the module it specifies cannot be imported because
it does not appear to exist.
@raise AttributeError: If an attribute of an object along the way cannot be
accessed, or a module along the way is not found.
@return: the Python object identified by 'name'.
"""
if not name:
raise InvalidName('Empty module name')
names = name.split('.')
# if the name starts or ends with a '.' or contains '..', the __import__
# will raise an 'Empty module name' error. This will provide a better error
# message.
if '' in names:
raise InvalidName(
"name must be a string giving a '.'-separated list of Python "
"identifiers, not %r" % (name,))
topLevelPackage = None
moduleNames = names[:]
while not topLevelPackage:
if moduleNames:
trialname = '.'.join(moduleNames)
try:
topLevelPackage = _importAndCheckStack(trialname)
except _NoModuleFound:
moduleNames.pop()
else:
if len(names) == 1:
raise ModuleNotFound("No module named %r" % (name,))
else:
raise ObjectNotFound('%r does not name an object' % (name,))
obj = topLevelPackage
for n in names[1:]:
obj = getattr(obj, n)
return obj
def macro(name, filename, source, **identifiers):
"""macro(name, source, **identifiers)
This allows you to create macro-like behaviors in python.
"""
if not identifiers.has_key('name'):
identifiers['name'] = name
source = source % identifiers
codeplace = "<%s (macro)>" % filename
code = compile(source, codeplace, 'exec')
# shield your eyes!
sm = sys.modules
tprm = "twisted.python.reflect.macros"
if not sm.has_key(tprm):
macros = new.module(tprm)
sm[tprm] = macros
macros.count = 0
macros = sm[tprm]
macros.count += 1
macroname = 'macro_' + str(macros.count)
tprmm = tprm + '.' + macroname
mymod = new.module(tprmm)
sys.modules[tprmm] = mymod
setattr(macros, macroname, mymod)
dict = mymod.__dict__
# Before we go on, I guess I should explain why I just did that. Basically
# it's a gross hack to get epydoc to work right, but the general idea is
# that it will be a useful aid in debugging in _any_ app which expects
# sys.modules to have the same globals as some function. For example, it
# would be useful if you were foolishly trying to pickle a wrapped function
# directly from a class that had been hooked.
exec code in dict, dict
return dict[name]
macro = deprecated(Version("Twisted", 8, 2, 0))(macro)
def _determineClass(x):
try:
return x.__class__
except:
return type(x)
def _determineClassName(x):
c = _determineClass(x)
try:
return c.__name__
except:
try:
return str(c)
except:
return '<BROKEN CLASS AT 0x%x>' % unsignedID(c)
def _safeFormat(formatter, o):
"""
Helper function for L{safe_repr} and L{safe_str}.
"""
try:
return formatter(o)
except:
io = StringIO()
traceback.print_exc(file=io)
className = _determineClassName(o)
tbValue = io.getvalue()
return "<%s instance at 0x%x with %s error:\n %s>" % (
className, unsignedID(o), formatter.__name__, tbValue)
def safe_repr(o):
"""
safe_repr(anything) -> string
Returns a string representation of an object, or a string containing a
traceback, if that object's __repr__ raised an exception.
"""
return _safeFormat(repr, o)
def safe_str(o):
"""
safe_str(anything) -> string
Returns a string representation of an object, or a string containing a
traceback, if that object's __str__ raised an exception.
"""
return _safeFormat(str, o)
##the following were factored out of usage
def allYourBase(classObj, baseClass=None):
"""allYourBase(classObj, baseClass=None) -> list of all base
classes that are subclasses of baseClass, unless it is None,
in which case all bases will be added.
"""
l = []
accumulateBases(classObj, l, baseClass)
return l
def accumulateBases(classObj, l, baseClass=None):
for base in classObj.__bases__:
if baseClass is None or issubclass(base, baseClass):
l.append(base)
accumulateBases(base, l, baseClass)
def prefixedMethodNames(classObj, prefix):
"""A list of method names with a given prefix in a given class.
"""
dct = {}
addMethodNamesToDict(classObj, dct, prefix)
return dct.keys()
def addMethodNamesToDict(classObj, dict, prefix, baseClass=None):
"""
addMethodNamesToDict(classObj, dict, prefix, baseClass=None) -> dict
this goes through 'classObj' (and its bases) and puts method names
starting with 'prefix' in 'dict' with a value of 1. if baseClass isn't
None, methods will only be added if classObj is-a baseClass
If the class in question has the methods 'prefix_methodname' and
'prefix_methodname2', the resulting dict should look something like:
{"methodname": 1, "methodname2": 1}.
"""
for base in classObj.__bases__:
addMethodNamesToDict(base, dict, prefix, baseClass)
if baseClass is None or baseClass in classObj.__bases__:
for name, method in classObj.__dict__.items():
optName = name[len(prefix):]
if ((type(method) is types.FunctionType)
and (name[:len(prefix)] == prefix)
and (len(optName))):
dict[optName] = 1
def prefixedMethods(obj, prefix=''):
"""A list of methods with a given prefix on a given instance.
"""
dct = {}
accumulateMethods(obj, dct, prefix)
return dct.values()
def accumulateMethods(obj, dict, prefix='', curClass=None):
"""accumulateMethods(instance, dict, prefix)
I recurse through the bases of instance.__class__, and add methods
beginning with 'prefix' to 'dict', in the form of
{'methodname':*instance*method_object}.
"""
if not curClass:
curClass = obj.__class__
for base in curClass.__bases__:
accumulateMethods(obj, dict, prefix, base)
for name, method in curClass.__dict__.items():
optName = name[len(prefix):]
if ((type(method) is types.FunctionType)
and (name[:len(prefix)] == prefix)
and (len(optName))):
dict[optName] = getattr(obj, name)
def accumulateClassDict(classObj, attr, adict, baseClass=None):
"""Accumulate all attributes of a given name in a class heirarchy into a single dictionary.
Assuming all class attributes of this name are dictionaries.
If any of the dictionaries being accumulated have the same key, the
one highest in the class heirarchy wins.
(XXX: If \"higest\" means \"closest to the starting class\".)
Ex::
| class Soy:
| properties = {\"taste\": \"bland\"}
|
| class Plant:
| properties = {\"colour\": \"green\"}
|
| class Seaweed(Plant):
| pass
|
| class Lunch(Soy, Seaweed):
| properties = {\"vegan\": 1 }
|
| dct = {}
|
| accumulateClassDict(Lunch, \"properties\", dct)
|
| print dct
{\"taste\": \"bland\", \"colour\": \"green\", \"vegan\": 1}
"""
for base in classObj.__bases__:
accumulateClassDict(base, attr, adict)
if baseClass is None or baseClass in classObj.__bases__:
adict.update(classObj.__dict__.get(attr, {}))
def accumulateClassList(classObj, attr, listObj, baseClass=None):
"""Accumulate all attributes of a given name in a class heirarchy into a single list.
Assuming all class attributes of this name are lists.
"""
for base in classObj.__bases__:
accumulateClassList(base, attr, listObj)
if baseClass is None or baseClass in classObj.__bases__:
listObj.extend(classObj.__dict__.get(attr, []))
def isSame(a, b):
return (a is b)
def isLike(a, b):
return (a == b)
def modgrep(goal):
return objgrep(sys.modules, goal, isLike, 'sys.modules')
def isOfType(start, goal):
return ((type(start) is goal) or
(isinstance(start, types.InstanceType) and
start.__class__ is goal))
def findInstances(start, t):
return objgrep(start, t, isOfType)
def objgrep(start, goal, eq=isLike, path='', paths=None, seen=None, showUnknowns=0, maxDepth=None):
'''An insanely CPU-intensive process for finding stuff.
'''
if paths is None:
paths = []
if seen is None:
seen = {}
if eq(start, goal):
paths.append(path)
if id(start) in seen:
if seen[id(start)] is start:
return
if maxDepth is not None:
if maxDepth == 0:
return
maxDepth -= 1
seen[id(start)] = start
if isinstance(start, types.DictionaryType):
for k, v in start.items():
objgrep(k, goal, eq, path+'{'+repr(v)+'}', paths, seen, showUnknowns, maxDepth)
objgrep(v, goal, eq, path+'['+repr(k)+']', paths, seen, showUnknowns, maxDepth)
elif isinstance(start, (list, tuple, deque)):
for idx in xrange(len(start)):
objgrep(start[idx], goal, eq, path+'['+str(idx)+']', paths, seen, showUnknowns, maxDepth)
elif isinstance(start, types.MethodType):
objgrep(start.im_self, goal, eq, path+'.im_self', paths, seen, showUnknowns, maxDepth)
objgrep(start.im_func, goal, eq, path+'.im_func', paths, seen, showUnknowns, maxDepth)
objgrep(start.im_class, goal, eq, path+'.im_class', paths, seen, showUnknowns, maxDepth)
elif hasattr(start, '__dict__'):
for k, v in start.__dict__.items():
objgrep(v, goal, eq, path+'.'+k, paths, seen, showUnknowns, maxDepth)
if isinstance(start, types.InstanceType):
objgrep(start.__class__, goal, eq, path+'.__class__', paths, seen, showUnknowns, maxDepth)
elif isinstance(start, weakref.ReferenceType):
objgrep(start(), goal, eq, path+'()', paths, seen, showUnknowns, maxDepth)
elif (isinstance(start, types.StringTypes+
(types.IntType, types.FunctionType,
types.BuiltinMethodType, RegexType, types.FloatType,
types.NoneType, types.FileType)) or
type(start).__name__ in ('wrapper_descriptor', 'method_descriptor',
'member_descriptor', 'getset_descriptor')):
pass
elif showUnknowns:
print 'unknown type', type(start), start
return paths
def filenameToModuleName(fn):
"""
Convert a name in the filesystem to the name of the Python module it is.
This is agressive about getting a module name back from a file; it will
always return a string. Agressive means 'sometimes wrong'; it won't look
at the Python path or try to do any error checking: don't use this method
unless you already know that the filename you're talking about is a Python
module.
"""
fullName = os.path.abspath(fn)
base = os.path.basename(fn)
if not base:
# this happens when fn ends with a path separator, just skit it
base = os.path.basename(fn[:-1])
modName = os.path.splitext(base)[0]
while 1:
fullName = os.path.dirname(fullName)
if os.path.exists(os.path.join(fullName, "__init__.py")):
modName = "%s.%s" % (os.path.basename(fullName), modName)
else:
break
return modName
__all__ = [
'InvalidName', 'ModuleNotFound', 'ObjectNotFound',
'ISNT', 'WAS', 'IS',
'Settable', 'AccessorType', 'PropertyAccessor', 'Accessor', 'Summer',
'QueueMethod', 'OriginalAccessor',
'funcinfo', 'fullFuncName', 'qual', 'getcurrent', 'getClass', 'isinst',
'namedModule', 'namedObject', 'namedClass', 'namedAny', 'macro',
'safe_repr', 'safe_str', 'allYourBase', 'accumulateBases',
'prefixedMethodNames', 'addMethodNamesToDict', 'prefixedMethods',
'accumulateClassDict', 'accumulateClassList', 'isSame', 'isLike',
'modgrep', 'isOfType', 'findInstances', 'objgrep', 'filenameToModuleName',
'fullyQualifiedName']
|