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[Python-Dev] PEP 409 update [was: PEP 409 - final?]
Yury Selivanovyselivanov.ml at gmail.com
Fri Feb 3 20:18:53 CET 2012
That's a bit far-fetched. Using same level argumentation we can utilizeeven `0`. `raise e from 0` (or `-1`), and use `0` object instead of Ellipsis.Anyways, if the PEP is not yet fully approved, I'm minus one on allowingof using anything other than Exception instance or None in 'raise from'statement.On 2012-02-03, at 2:03 PM, Ethan Furman wrote:> Yury Selivanov wrote:>> On 2012-02-03, at 1:20 PM, Guido van Rossum wrote:>>> Please. Let's stop this. There is no known use case to ever write>>> that. We're just not putting specific measures to prevent it. Writing>>>>>>>>> a = ...>>> Is likewise cute but not very informative. But it is valid syntax.>> Well, right now you'll get TypeError if you want to raise an exception>> from something that is not an exception. 'raise from None' will>> loosen the check allowing None values, in the 'raise from' statement,>> but that should be it.>> To achieve the same effect as 'raise from ...' just do 'e.__cause__ = ...'.>> On the question of using Ellipsis instead of some new singleton like>> __NoContext__: how's Ellipsis semantically related to exceptions after all?>>> Merrian Webster says:> ---------------------> el·lip·sis> noun \i-ˈlip-səs, e-\> plural el·lip·ses\-ˌsēz\> Definition of ELLIPSIS> 1> a : the omission of one or more words that are obviously understood but that must be supplied to make a construction grammatically complete> --------------------->> Relation to exceptions:> Two places to look: __context__ and __cause__> Priority? __cause__> When do we check __context__? if __cause__ is omitted (or Ellipsis)>> ~Ethan~
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