#16316: cached_function and cached_method for unhashable elements
-------------------------------------+-------------------------------------
Reporter: saraedum | Owner:
Type: enhancement | Status: needs_review
Priority: minor | Milestone: sage-6.3
Component: misc | Resolution:
Keywords: | Merged in:
Authors: Julian Rueth | Reviewers: Peter Bruin, Travis
Report Upstream: N/A | Scrimshaw
Branch: | Work issues:
u/tscrim/ticket/16316 | Commit:
Dependencies: #16251 | 7a9a6b2a3e4a68bfd3c9d8d6556a883e1d1161e0
| Stopgaps:
-------------------------------------+-------------------------------------
Comment (by SimonKing):
Replying to [comment:29 tscrim]:
> Also in short, `@lazy_attribute` makes a method (with no input args)
behave like an attribute and is only called when necessary. IIRC it's
faster than usual python attribute access and using `@cached_method` with
no args.
That's not correct. At least when you have a Python class, a lazy
attribute ''will'' be a plain python attribute after the first access.
Indeed, a lazy attribute `L` defined for some class `C` has a `__get__`
method, so that `L.__get__(O, C)` assigns the output value to `O.L`, for
an instance `O` of `C`. In other words, it overrides itself by the return
value and thus is exactly as fast as a usual python attribute, after the
first access.
However, if `C` is a Cython class, attribute assignment does not always
work. Hence, in this case, `L.__get__(O,C)` will not be able to assign the
return value to `O.L`. By consequence, the `__get__` method will be called
upon each single access. Hence, if I see that correctly, the performance
will be worse than calling a method.
--
Ticket URL: <http://trac.sagemath.org/ticket/16316#comment:33>
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 unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
