/usr/lib/python2.7/dist-packages/formencode/declarative.py is in python-formencode 1.2.6-1ubuntu1.
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Declarative objects for FormEncode.
Declarative objects have a simple protocol: you can use classes in
lieu of instances and they are equivalent, and any keyword arguments
you give to the constructor will override those instance variables.
(So if a class is received, we'll simply instantiate an instance with
no arguments).
You can provide a variable __unpackargs__ (a list of strings), and if
the constructor is called with non-keyword arguments they will be
interpreted as the given keyword arguments.
If __unpackargs__ is ('*', name), then all the arguments will be put
in a variable by that name.
Also, you can define a __classinit__(cls, new_attrs) method, which
will be called when the class is created (including subclasses).
"""
import copy
import new
from itertools import count
class classinstancemethod(object):
"""
Acts like a class method when called from a class, like an
instance method when called by an instance. The method should
take two arguments, 'self' and 'cls'; one of these will be None
depending on how the method was called.
"""
def __init__(self, func):
self.func = func
def __get__(self, obj, type=None):
return _methodwrapper(self.func, obj=obj, type=type)
class _methodwrapper(object):
def __init__(self, func, obj, type):
self.func = func
self.obj = obj
self.type = type
def __call__(self, *args, **kw):
assert 'self' not in kw and 'cls' not in kw, (
"You cannot use 'self' or 'cls' arguments to a "
"classinstancemethod")
return self.func(*((self.obj, self.type) + args), **kw)
def __repr__(self):
if self.obj is None:
return ('<bound class method %s.%s>'
% (self.type.__name__, self.func.func_name))
else:
return ('<bound method %s.%s of %r>'
% (self.type.__name__, self.func.func_name, self.obj))
class DeclarativeMeta(type):
def __new__(meta, class_name, bases, new_attrs):
cls = type.__new__(meta, class_name, bases, new_attrs)
for name in cls.__mutableattributes__:
setattr(cls, name, copy.copy(getattr(cls, name)))
cls.declarative_count = cls.counter.next()
if ('__classinit__' in new_attrs
and not isinstance(cls.__classinit__, staticmethod)):
setattr(cls, '__classinit__',
staticmethod(cls.__classinit__.im_func))
cls.__classinit__(cls, new_attrs)
names = getattr(cls, '__singletonmethods__', None)
if names:
for name in names:
meth = cls.__dict__.get(name)
if meth and not isinstance(meth, singletonmethod):
setattr(cls, name, singletonmethod(meth))
return cls
class singletonmethod(object):
"""
For Declarative subclasses, this decorator will call the method
on the cls.singleton() object if called as a class method (or
as normal if called as an instance method).
"""
def __init__(self, func):
self.func = func
def __get__(self, obj, type=None):
if obj is None:
obj = type.singleton()
if type is None:
type = obj.__class__
return new.instancemethod(self.func, obj, type)
class Declarative(object):
__unpackargs__ = ()
__mutableattributes__ = ()
__metaclass__ = DeclarativeMeta
__singletonmethods__ = ()
counter = count()
def __classinit__(cls, new_attrs):
pass
def __init__(self, *args, **kw):
if self.__unpackargs__ and self.__unpackargs__[0] == '*':
assert len(self.__unpackargs__) == 2, (
"When using __unpackargs__ = ('*', varname),"
" you must only provide a single variable name"
" (you gave %r)" % self.__unpackargs__)
name = self.__unpackargs__[1]
if name in kw:
raise TypeError(
"keyword parameter '%s' was given by position and name"
% name)
kw[name] = args
else:
if len(args) > len(self.__unpackargs__):
raise TypeError(
'%s() takes at most %i arguments (%i given)'
% (self.__class__.__name__,
len(self.__unpackargs__),
len(args)))
for name, arg in zip(self.__unpackargs__, args):
if name in kw:
raise TypeError(
"keyword parameter '%s' was given by position and name"
% name)
kw[name] = arg
for name in self.__mutableattributes__:
if name not in kw:
setattr(self, name, copy.copy(getattr(self, name)))
for name, value in kw.items():
setattr(self, name, value)
if 'declarative_count' not in kw:
self.declarative_count = self.counter.next()
self.__initargs__(kw)
def __initargs__(self, new_attrs):
pass
def __call__(self, *args, **kw):
current = self.__dict__.copy()
current.update(kw)
return self.__class__(*args, **current)
def singleton(cls):
name = '_%s__singleton' % cls.__name__
if not hasattr(cls, name):
try:
setattr(cls, name, cls(declarative_count=cls.declarative_count))
except TypeError: # takes arguments
setattr(cls, name, cls)
return getattr(cls, name)
singleton = classmethod(singleton)
def __sourcerepr__(self, source, binding=None):
if binding and len(self.__dict__) > 3:
return self._source_repr_class(source, binding=binding)
else:
vals = self.__dict__.copy()
if 'declarative_count' in vals:
del vals['declarative_count']
args = []
if (self.__unpackargs__ and self.__unpackargs__[0] == '*'
and self.__unpackargs__[1] in vals):
v = vals[self.__unpackargs__[1]]
if isinstance(v, (list, int)):
args.extend(map(source.makeRepr, v))
del v[self.__unpackargs__[1]]
for name in self.__unpackargs__:
if name in vals:
args.append(source.makeRepr(vals[name]))
del vals[name]
else:
break
args.extend(['%s=%s' % (name, source.makeRepr(value))
for (name, value) in vals.items()])
return '%s(%s)' % (self.__class__.__name__,
', '.join(args))
def _source_repr_class(self, source, binding=None):
d = self.__dict__.copy()
if 'declarative_count' in d:
del d['declarative_count']
return source.makeClass(self, binding, d,
(self.__class__,))
def __classsourcerepr__(cls, source, binding=None):
d = cls.__dict__.copy()
del d['declarative_count']
return source.makeClass(cls, binding or cls.__name__, d,
cls.__bases__)
__classsourcerepr__ = classmethod(__classsourcerepr__)
def __repr__(self, cls):
if self:
name = '%s object' % self.__class__.__name__
v = self.__dict__.copy()
else:
name = '%s class' % cls.__name__
v = cls.__dict__.copy()
if 'declarative_count' in v:
name = '%s %i' % (name, v.pop('declarative_count'))
names = v.keys()
names.sort()
args = []
for n in self._repr_vars(names):
if v[n] is self:
args.append('%s=self' % n)
else:
args.append('%s=%r' % (n, v[n]))
if not args:
return '<%s>' % name
else:
return '<%s %s>' % (name, ' '.join(args))
__repr__ = classinstancemethod(__repr__)
def _repr_vars(dictNames):
names = [n for n in dictNames
if not n.startswith('_') and n != 'declarative_count']
names.sort()
return names
_repr_vars = staticmethod(_repr_vars)
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