[Python-Dev] PEP 362: 4th edition

[Nick Coghlan]

On Tue, Jun 19, 2012 at 7:06 AM, Jim Jewett <jimjjewett at gmail.com> wrote:
> Correct; it should be redundant.  Signature.kwargsparameter should be
> the same object that occurs as the nth element of
> Signature.parameters.values().  It is just more convenient to retrieve
> the parameter directly than it is to iterate through a collection
> inspecting each element for the value of a specific attribute.

I suspect in 3.4 we will add the following additional convenience properties:

 Signature.positional -> list[Parameter]
    List of POSITIONAL_ONLY and KEYWORD_OR_POSITIONAL parameters
 Signature.var_positional -> None or Parameter
    Reference to the VAR_POSITIONAL parameter, if any
 Signature.keyword -> dict{name:Parameter}
    Mapping of all KEYWORD_ONLY and KEYWORD_OR_POSITIONAL parameters
 Signature.var_keyword -> None or Parameter
    Reference to the VAR_KEYWORD parameter, if any

However, I don't think we should add such convenience properties
*right now*. One step at a time.

> __eq__ can can an _eq_fields attribute to see which other attributes
> matter -- but it makes more sense for that to be (sub-) class
> property.

Only if you accept the premise that there are other possible parameter
binding behaviours beyond the five already defined.
Hypergeneralisation is a great way to make an API far more complex
than it needs to be.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia