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Added Michele Simionato's decorator module, for use in debug.py
 - Legacy-Id: 4934
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‎decorator.py‎

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########################## LICENCE ###############################
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# Copyright (c) 2005-2012, Michele Simionato
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# All rights reserved.
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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# Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# Redistributions in bytecode form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
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# TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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# DAMAGE.
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"""
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Decorator module, see http://pypi.python.org/pypi/decorator
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for the documentation.
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"""
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__version__ = '3.4.0'
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__all__ = ["decorator", "FunctionMaker", "contextmanager"]
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import sys, re, inspect
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if sys.version >= '3':
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from inspect import getfullargspec
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def get_init(cls):
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return cls.__init__
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else:
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class getfullargspec(object):
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"A quick and dirty replacement for getfullargspec for Python 2.X"
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def __init__(self, f):
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self.args, self.varargs, self.varkw, self.defaults = \
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inspect.getargspec(f)
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self.kwonlyargs = []
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self.kwonlydefaults = None
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def __iter__(self):
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yield self.args
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yield self.varargs
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yield self.varkw
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yield self.defaults
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def get_init(cls):
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return cls.__init__.im_func
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DEF = re.compile('\s*def\s*([_\w][_\w\d]*)\s*\(')
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# basic functionality
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class FunctionMaker(object):
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"""
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An object with the ability to create functions with a given signature.
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It has attributes name, doc, module, signature, defaults, dict and
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methods update and make.
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"""
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def __init__(self, func=None, name=None, signature=None,
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defaults=None, doc=None, module=None, funcdict=None):
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self.shortsignature = signature
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if func:
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# func can be a class or a callable, but not an instance method
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self.name = func.__name__
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if self.name == '<lambda>': # small hack for lambda functions
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self.name = '_lambda_'
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self.doc = func.__doc__
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self.module = func.__module__
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if inspect.isfunction(func):
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argspec = getfullargspec(func)
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self.annotations = getattr(func, '__annotations__', {})
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for a in ('args', 'varargs', 'varkw', 'defaults', 'kwonlyargs',
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'kwonlydefaults'):
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setattr(self, a, getattr(argspec, a))
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for i, arg in enumerate(self.args):
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setattr(self, 'arg%d' % i, arg)
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if sys.version < '3': # easy way
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self.shortsignature = self.signature = \
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inspect.formatargspec(
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formatvalue=lambda val: "", *argspec)[1:-1]
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else: # Python 3 way
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allargs = list(self.args)
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allshortargs = list(self.args)
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if self.varargs:
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allargs.append('*' + self.varargs)
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allshortargs.append('*' + self.varargs)
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elif self.kwonlyargs:
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allargs.append('*') # single star syntax
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for a in self.kwonlyargs:
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allargs.append('%s=None' % a)
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allshortargs.append('%s=%s' % (a, a))
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if self.varkw:
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allargs.append('**' + self.varkw)
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allshortargs.append('**' + self.varkw)
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self.signature = ', '.join(allargs)
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self.shortsignature = ', '.join(allshortargs)
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self.dict = func.__dict__.copy()
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# func=None happens when decorating a caller
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if name:
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self.name = name
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if signature is not None:
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self.signature = signature
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if defaults:
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self.defaults = defaults
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if doc:
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self.doc = doc
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if module:
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self.module = module
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if funcdict:
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self.dict = funcdict
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# check existence required attributes
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assert hasattr(self, 'name')
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if not hasattr(self, 'signature'):
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raise TypeError('You are decorating a non function: %s' % func)
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def update(self, func, **kw):
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"Update the signature of func with the data in self"
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func.__name__ = self.name
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func.__doc__ = getattr(self, 'doc', None)
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func.__dict__ = getattr(self, 'dict', {})
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func.func_defaults = getattr(self, 'defaults', ())
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func.__kwdefaults__ = getattr(self, 'kwonlydefaults', None)
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func.__annotations__ = getattr(self, 'annotations', None)
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callermodule = sys._getframe(3).f_globals.get('__name__', '?')
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func.__module__ = getattr(self, 'module', callermodule)
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func.__dict__.update(kw)
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def make(self, src_templ, evaldict=None, addsource=False, **attrs):
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"Make a new function from a given template and update the signature"
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src = src_templ % vars(self) # expand name and signature
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evaldict = evaldict or {}
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mo = DEF.match(src)
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if mo is None:
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raise SyntaxError('not a valid function template\n%s' % src)
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name = mo.group(1) # extract the function name
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names = set([name] + [arg.strip(' *') for arg in
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self.shortsignature.split(',')])
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for n in names:
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if n in ('_func_', '_call_'):
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raise NameError('%s is overridden in\n%s' % (n, src))
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if not src.endswith('\n'): # add a newline just for safety
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src += '\n' # this is needed in old versions of Python
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try:
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code = compile(src, '<string>', 'single')
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# print >> sys.stderr, 'Compiling %s' % src
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exec code in evaldict
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except:
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print >> sys.stderr, 'Error in generated code:'
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print >> sys.stderr, src
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raise
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func = evaldict[name]
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if addsource:
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attrs['__source__'] = src
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self.update(func, **attrs)
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return func
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@classmethod
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def create(cls, obj, body, evaldict, defaults=None,
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doc=None, module=None, addsource=True, **attrs):
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"""
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Create a function from the strings name, signature and body.
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evaldict is the evaluation dictionary. If addsource is true an attribute
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__source__ is added to the result. The attributes attrs are added,
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if any.
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"""
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if isinstance(obj, str): # "name(signature)"
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name, rest = obj.strip().split('(', 1)
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signature = rest[:-1] #strip a right parens
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func = None
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else: # a function
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name = None
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signature = None
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func = obj
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self = cls(func, name, signature, defaults, doc, module)
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ibody = '\n'.join(' ' + line for line in body.splitlines())
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return self.make('def %(name)s(%(signature)s):\n' + ibody,
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evaldict, addsource, **attrs)
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def decorator(caller, func=None):
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"""
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decorator(caller) converts a caller function into a decorator;
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decorator(caller, func) decorates a function using a caller.
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"""
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if func is not None: # returns a decorated function
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evaldict = func.func_globals.copy()
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evaldict['_call_'] = caller
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evaldict['_func_'] = func
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return FunctionMaker.create(
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func, "return _call_(_func_, %(shortsignature)s)",
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evaldict, undecorated=func, __wrapped__=func)
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else: # returns a decorator
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if inspect.isclass(caller):
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name = caller.__name__.lower()
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callerfunc = get_init(caller)
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doc = 'decorator(%s) converts functions/generators into ' \
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'factories of %s objects' % (caller.__name__, caller.__name__)
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fun = getfullargspec(callerfunc).args[1] # second arg
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elif inspect.isfunction(caller):
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name = '_lambda_' if caller.__name__ == '<lambda>' \
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else caller.__name__
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callerfunc = caller
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doc = caller.__doc__
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fun = getfullargspec(callerfunc).args[0] # first arg
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else: # assume caller is an object with a __call__ method
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name = caller.__class__.__name__.lower()
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callerfunc = caller.__call__.im_func
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doc = caller.__call__.__doc__
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fun = getfullargspec(callerfunc).args[1] # second arg
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evaldict = callerfunc.func_globals.copy()
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evaldict['_call_'] = caller
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evaldict['decorator'] = decorator
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return FunctionMaker.create(
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'%s(%s)' % (name, fun),
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'return decorator(_call_, %s)' % fun,
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evaldict, undecorated=caller, __wrapped__=caller,
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doc=doc, module=caller.__module__)
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######################### contextmanager ########################
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def __call__(self, func):
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'Context manager decorator'
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return FunctionMaker.create(
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func, "with _self_: return _func_(%(shortsignature)s)",
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dict(_self_=self, _func_=func), __wrapped__=func)
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try: # Python >= 3.2
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from contextlib import _GeneratorContextManager
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ContextManager = type(
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'ContextManager', (_GeneratorContextManager,), dict(__call__=__call__))
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except ImportError: # Python >= 2.5
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from contextlib import GeneratorContextManager
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def __init__(self, f, *a, **k):
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return GeneratorContextManager.__init__(self, f(*a, **k))
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ContextManager = type(
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'ContextManager', (GeneratorContextManager,),
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dict(__call__=__call__, __init__=__init__))
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contextmanager = decorator(ContextManager)

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