#11999: Renaming lazy attributes
-------------------------+--------------------------------------------------
Reporter: SimonKing | Owner: jason
Type: defect | Status: new
Priority: major | Milestone: sage-4.8
Component: misc | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: Author
Merged: | Dependencies:
-------------------------+--------------------------------------------------
Currently, it is not possible to take an existing lazy attribute and
assign it to a different name. The reason is that a lazy attribute
overwrites itself by a usual attribute of its `__name__`. But `__name__`
is created during initialisation of the lazy attribute. Thus, we have the
following example:
{{{
sage: class Foo(object):
....: @lazy_attribute
....: def _bar(self):
....: return 5
....: bar = _bar
....:
sage: f = Foo()
sage: f.bar # it seems to work,...
5
sage: f.__dict__['bar'] # ... but the lazy attribute has not become a
usual attribute
Traceback (most recent call last):
...
KeyError: 'bar'
sage: f.__dict__['_bar']
5
}}}
By consequence, `f.bar` is much slower than `f._bar`:
{{{
sage: %timeit f.bar
625 loops, best of 3: 2.78 µs per loop
sage: %timeit f._bar
625 loops, best of 3: 185 ns per loop
}}}
I suggest to provide lazy attributes with a method `rename()`, returning a
copy of that lazy attribute under a new name.
Example, which is a doc test of my patch:
{{{
sage: class Foo(object):
....: @lazy_attribute
....: def _bar(self):
....: return 5
....: bar = _bar.rename("bar")
....:
sage: f = Foo()
sage: f.bar
5
sage: f.__dict__['bar']
5
sage: %timeit f.bar
625 loops, best of 3: 184 ns per loop
sage: %timeit f._bar
625 loops, best of 3: 184 ns per loop
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11999>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
