[Python-3000] PEP 3124 - Overloading, Generic Functions, Interfaces, etc. (original) (raw)

Phillip J. Eby pje at telecommunity.com
Thu May 10 17:47:19 CEST 2007

At 02:40 PM 5/10/2007 +1200, Greg Ewing wrote:

Phillip J. Eby wrote: > For > example, objects to be documented with pydoc currently have to > reverse engineer a bunch of inspection code, while in a GF-based > design they'd just add methods.

There's a problem with this that I haven't seen a good answer to yet. To add a method to a generic function, you have to import the module that defines the base function. So any module that wants its objects documented in a custom way ends up depending on pydoc.

Using the "Importing" package from the Cheeseshop:

def register_pydoc(pydoc):

 @when(pydoc.get_signature)
 def signature_for_mytype(ob:MyType)
     # etc.

 @when(pydoc.get_contents)
 def contents_for_mytype(ob:MyType)
     # etc.

from peak.util.imports import whenImported whenImported('pydoc', register_pydoc)

I certainly wouldn't object to making 'whenImported' and its friends a part of the stdlib.

There's also the possibility that other documentation systems could make use of the same protocol if it's designed appropriately, whereas extending pydoc-defined generic functions benefits pydoc and nothing else.

Of course; it's actually somewhat more likely that the basic GFs should actually live in "inspect" (or something like it) rather than in "pydoc" per se.

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