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https://github.com/djohnlewis/stackdump
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Initial commit. Still building up the env and some parsing code.
This commit is contained in:
Samuel Lai
232
python/packages/formencode/declarative.py
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232
python/packages/formencode/declarative.py
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"""
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Declarative objects for FormEncode.
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Declarative objects have a simple protocol: you can use classes in
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lieu of instances and they are equivalent, and any keyword arguments
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you give to the constructor will override those instance variables.
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(So if a class is received, we'll simply instantiate an instance with
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no arguments).
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You can provide a variable __unpackargs__ (a list of strings), and if
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the constructor is called with non-keyword arguments they will be
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interpreted as the given keyword arguments.
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If __unpackargs__ is ('*', name), then all the arguments will be put
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in a variable by that name.
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Also, you can define a __classinit__(cls, new_attrs) method, which
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will be called when the class is created (including subclasses).
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"""
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import copy
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import new
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from itertools import count
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class classinstancemethod(object):
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"""
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Acts like a class method when called from a class, like an
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instance method when called by an instance. The method should
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take two arguments, 'self' and 'cls'; one of these will be None
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depending on how the method was called.
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"""
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def __init__(self, func):
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self.func = func
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def __get__(self, obj, type=None):
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return _methodwrapper(self.func, obj=obj, type=type)
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class _methodwrapper(object):
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def __init__(self, func, obj, type):
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self.func = func
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self.obj = obj
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self.type = type
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def __call__(self, *args, **kw):
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assert 'self' not in kw and 'cls' not in kw, (
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"You cannot use 'self' or 'cls' arguments to a "
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"classinstancemethod")
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return self.func(*((self.obj, self.type) + args), **kw)
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def __repr__(self):
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if self.obj is None:
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return ('<bound class method %s.%s>'
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% (self.type.__name__, self.func.func_name))
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else:
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return ('<bound method %s.%s of %r>'
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% (self.type.__name__, self.func.func_name, self.obj))
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class DeclarativeMeta(type):
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def __new__(meta, class_name, bases, new_attrs):
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cls = type.__new__(meta, class_name, bases, new_attrs)
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for name in cls.__mutableattributes__:
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setattr(cls, name, copy.copy(getattr(cls, name)))
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cls.declarative_count = cls.counter.next()
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if ('__classinit__' in new_attrs
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and not isinstance(cls.__classinit__, staticmethod)):
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setattr(cls, '__classinit__',
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staticmethod(cls.__classinit__.im_func))
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cls.__classinit__(cls, new_attrs)
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names = getattr(cls, '__singletonmethods__', None)
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if names:
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for name in names:
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meth = cls.__dict__.get(name)
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if meth and not isinstance(meth, singletonmethod):
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setattr(cls, name, singletonmethod(meth))
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return cls
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class singletonmethod(object):
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"""
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For Declarative subclasses, this decorator will call the method
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on the cls.singleton() object if called as a class method (or
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as normal if called as an instance method).
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"""
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def __init__(self, func):
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self.func = func
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def __get__(self, obj, type=None):
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if obj is None:
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obj = type.singleton()
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if type is None:
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type = obj.__class__
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return new.instancemethod(self.func, obj, type)
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class Declarative(object):
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__unpackargs__ = ()
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__mutableattributes__ = ()
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__metaclass__ = DeclarativeMeta
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__singletonmethods__ = ()
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counter = count()
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def __classinit__(cls, new_attrs):
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pass
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def __init__(self, *args, **kw):
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if self.__unpackargs__ and self.__unpackargs__[0] == '*':
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assert len(self.__unpackargs__) == 2, (
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"When using __unpackargs__ = ('*', varname),"
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" you must only provide a single variable name"
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" (you gave %r)" % self.__unpackargs__)
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name = self.__unpackargs__[1]
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if name in kw:
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raise TypeError(
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"keyword parameter '%s' was given by position and name"
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% name)
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kw[name] = args
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else:
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if len(args) > len(self.__unpackargs__):
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raise TypeError(
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'%s() takes at most %i arguments (%i given)'
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% (self.__class__.__name__,
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len(self.__unpackargs__),
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len(args)))
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for name, arg in zip(self.__unpackargs__, args):
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if name in kw:
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raise TypeError(
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"keyword parameter '%s' was given by position and name"
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% name)
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kw[name] = arg
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for name in self.__mutableattributes__:
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if name not in kw:
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setattr(self, name, copy.copy(getattr(self, name)))
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for name, value in kw.items():
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setattr(self, name, value)
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if 'declarative_count' not in kw:
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self.declarative_count = self.counter.next()
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self.__initargs__(kw)
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def __initargs__(self, new_attrs):
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pass
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def __call__(self, *args, **kw):
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current = self.__dict__.copy()
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current.update(kw)
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return self.__class__(*args, **current)
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def singleton(cls):
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name = '_%s__singleton' % cls.__name__
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if not hasattr(cls, name):
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setattr(cls, name, cls(declarative_count=cls.declarative_count))
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return getattr(cls, name)
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singleton = classmethod(singleton)
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def __sourcerepr__(self, source, binding=None):
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if binding and len(self.__dict__) > 3:
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return self._source_repr_class(source, binding=binding)
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else:
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vals = self.__dict__.copy()
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if 'declarative_count' in vals:
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del vals['declarative_count']
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args = []
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if (self.__unpackargs__ and self.__unpackargs__[0] == '*'
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and self.__unpackargs__[1] in vals):
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v = vals[self.__unpackargs__[1]]
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if isinstance(v, (list, int)):
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args.extend(map(source.makeRepr, v))
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del v[self.__unpackargs__[1]]
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for name in self.__unpackargs__:
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if name in vals:
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args.append(source.makeRepr(vals[name]))
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del vals[name]
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else:
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break
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args.extend(['%s=%s' % (name, source.makeRepr(value))
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for (name, value) in vals.items()])
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return '%s(%s)' % (self.__class__.__name__,
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', '.join(args))
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def _source_repr_class(self, source, binding=None):
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d = self.__dict__.copy()
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if 'declarative_count' in d:
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del d['declarative_count']
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return source.makeClass(self, binding, d,
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(self.__class__,))
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def __classsourcerepr__(cls, source, binding=None):
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d = cls.__dict__.copy()
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del d['declarative_count']
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return source.makeClass(cls, binding or cls.__name__, d,
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cls.__bases__)
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__classsourcerepr__ = classmethod(__classsourcerepr__)
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def __repr__(self, cls):
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if self:
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name = '%s object' % self.__class__.__name__
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v = self.__dict__.copy()
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else:
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name = '%s class' % cls.__name__
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v = cls.__dict__.copy()
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if 'declarative_count' in v:
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name = '%s %i' % (name, v.pop('declarative_count'))
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names = v.keys()
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args = []
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for n in self._repr_vars(names):
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args.append('%s=%r' % (n, v[n]))
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if not args:
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return '<%s>' % name
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else:
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return '<%s %s>' % (name, ' '.join(args))
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def _repr_vars(dictNames):
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names = [n for n in dictNames
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if not n.startswith('_') and n != 'declarative_count']
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names.sort()
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return names
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_repr_vars = staticmethod(_repr_vars)
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__repr__ = classinstancemethod(__repr__)
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