[Python-Dev] pep 362 - 5th edition (original) (raw)

Yury Selivanov yselivanov.ml at gmail.com
Wed Jun 20 05:51:56 CEST 2012

On 2012-06-19, at 10:16 PM, Nick Coghlan wrote:

On Wed, Jun 20, 2012 at 11:22 AM, Yury Selivanov <yselivanov.ml at gmail.com> wrote:

On 2012-06-19, at 8:39 PM, Nick Coghlan wrote:

If we even keep that at all for the initial version of the API, the direct "default" and "annotation" attributes would just be read-only properties that accessed the "optional" container (reporting AttributeError if the corresponding attribute was missing)

+0. I think that 'optional' is a bit unusual attribute for the stdlib, but it will work if we make Signature immutable. The name isn't great, but the mapping is a lot more convenient when you need to handle the case of attributes potentially being missing.

What if instead of 'optional', we have 'base_signature' (or 'from_signature')?

sig = signature(func)
params = OrderedDict(tuple(sig.parameters.items())[1:])
new_sig = Signature(params, base_signature=sig)

And for Paramater:

param = sig.parameters['foo']

param1 = Parameter('bar', base_parameter=param)
param2 = Parameter('spam', annotation=int, base_parameter=param)
param3 = Parameter(base_parameter=param)
param4 = Parameter(default=42, base_parameter=param)

So 'base_parameter' will be a template from which Parameter's constructor will copy the missing arguments.

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