[with patch, positive review] Add support for lazy attributes via a decorator

[nthiery]

The lazy-attribute-...-nt patch on the sage-combinat patch servers is a first implementation of lazy attributes (see the doc in the patch). Comments and alternative implementations welcome! See the current caveats in the doc

Cheers,

Nicolas

[nthiery]

Patch

[nthiery]

In case I did not make myself clear: this patch is *not* ready for insertion in sage. It's more of a request for comments!

[mvngu]

Replying to nthiery:

In case I did not make myself clear: this patch is *not* ready for insertion in sage. It's more of a request for comments!

Here are some possible fixes for improving the documentation of the patch lazy_attributes-4371-nt.patch:

1.

-easilly override a given attribute; you don't need to call the
+easily override a given attribute; you don't need to call the

2.

-the internal dictionnary of the object:
+the internal dictionary of the object:

Otherwise, the doc looks OK to me.

[nthiery]

Fixes applied. Thanks. Lazy attributes now work well with new style classes:

​http://sage.math.washington.edu:2144/file/03b4130fb25d/lazy_attributes-4371-nt.patch

[mvngu]

Replying to nthiery:

Fixes applied. Thanks. Lazy attributes now work well with new style classes:

​http://sage.math.washington.edu:2144/file/03b4130fb25d/lazy_attributes-4371-nt.patch

For your new patch at the above URL, here's a fix to improve your documentation:

-Invoking Descriptors in the python reference manual).
+Invoking Descriptors in the Python reference manual).

[mabshoff]

Nicolas,

should this patch be reviewed?

Cheers,

Michael

[nthiery]

Comments on it are more than welcome (in particular for the hasattr feature). No need to waste time on a complete final review though.

Thanks,

Nicolas

[nthiery]

Ready for review. Not all desired features are implemented, but we need the bulk for upcoming patches.

[rlm]

Apply lazy_attributes-4371-nt.2.patch only.

[mabshoff]

For the record note that

• __init___
• __get__

do not have doctests, but this will not stop the merge in this case :)

Cheers,

Michael

[mabshoff]

Merged lazy_attributes-4371-nt.2.patch in Sage 3.3.rc1.

Cheers,

Michael

[nthiery]

Thanks Michael and Robert.

Michael: could you please fold the patch into sage-3.3 on the sage-combinat patch server?

Thanks!