#12953: Bindable classes
---------------------------+------------------------------------------------
Reporter: nthiery | Owner: jason
Type: enhancement | Status: new
Priority: major | Milestone: sage-5.1
Component: misc | Keywords:
Work issues: | Report Upstream: N/A
Reviewers: | Authors: Nicolas M. Thiéry
Merged in: | Dependencies:
Stopgaps: |
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From the documentation:
{{{
Bindable classes
This class implements a binding behavior for nested classes that
derive from it.
EXAMPLES:
Let us consider the following class ``Outer`` with a nested class
``Inner``::
sage: from sage.misc.nested_class import NestedClassMetaclass
sage: class Outer:
... __metaclass__ = NestedClassMetaclass # workaround for
python pickling bug
... def f(self, *args):
... print self, args
...
... @staticmethod
... def f_static(*args):
... print args
...
... class Inner:
... def __init__(self, *args):
... print args
sage: obj = Outer()
By default, when Inner is a class nested in Outer, accessing
``obj.Inner`` returns the ``Inner`` class as is::
sage: obj.Inner is Outer.Inner
True
In particular, ``obj`` is completely ignored in the following call::
sage: x = obj.Inner(1,2,3)
(1, 2, 3)
This is similar to what happens with a staticmethod::
sage: obj.f_static(1,2,3)
(1, 2, 3)
In some cases, we would want instead Inner to receive ``obj`` as
parameter, like in a usual method call::
sage: obj.f(1,2,3)
<__main__.Outer object at ...> (1, 2, 3)
To this end, ``obj.f`` returns a *bound method*::
sage: obj.f
<bound method Outer.f of <__main__.Outer object at ...>>
so that ``obj.f(1,2,3)`` is equivalent to::
sage: Outer.f(obj, 1,2,3)
<__main__.Outer object at ...> (1, 2, 3)
``BindableClass`` gives this binding behavior to all its subclasses::
sage: from sage.misc.bindable_class import BindableClass
sage: class Outer:
... __metaclass__ = NestedClassMetaclass # workaround for
python pickling bug
...
... class Inner(BindableClass):
... " some documentation "
... def __init__(self, obj, *args):
... print obj, args
Now, ``obj.Inner(1,2,3)`` is equivalent to Outer.Inner(obj, 1,2,3)::
sage: obj = Outer()
sage: x = obj.Inner(1,2,3)
<__main__.Outer object at ...> (1, 2, 3)
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12953>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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