Ohhhhh, another D-word! I really like distinct.
On Sat, May 28, 2016 at 8:19 AM, Steve Dower <steve.dower at python.org> wrote:
> Did anyone suggest "distinct type alias"?
>
> Regardless of what name, I'm fairly sure people will call it whatever the
> function to create it is called. So if the function is
> typings.distinguish_type(...), then distinguished will stick.
>
> Top-posted from my Windows Phone
> ________________________________
> From: Guido van Rossum
> Sent: 5/28/2016 7:38
> To: Steven D'Aprano
> Cc: Python-Dev
> Subject: Re: [Python-Dev] Adding NewType() to PEP 484
>
> Just to add to the list of options, Twitter also came up with
>
> - invention
>
> - DomainType
>
> - TypedAlias
>
> But seriously I think we should just decide between Derived Type and
> Distinguished Type [Alias].
>
> The latter comes from the idea that when you write e.g.
>
> UserId = int
>
> then UserId is a type alias (that's existing PEP 484 terminology) and
> the type checker doesn't distinguish it from int -- you can use it in
> places where you logically expect a UserId but to the type checker
> those variables have the type int.
>
> There is even a neat potential "origin story" that would explain why
> we'd call it Distinguished Type Alias.
>
> The story is about gradually converting a large code base to being
> consistent: initially you make UserId a regular type alias and you
> start putting it in your code incrementally, making sure it has no
> mypy errors as you go (but this just treats it as an int). After days,
> when you think you are done, you change UserId to a distinguished type
> alias and then mypy will point out the places where you've missed
> something or you're doing something questionable with user IDs.
>
> And yes, in the wider context of subclassing, Derived Type is probably
> confusing because a subclass is also called a derived class.
>
>
> On Sat, May 28, 2016 at 5:24 AM, Steven D'Aprano <steve at pearwood.info>
> wrote:
>> On Fri, May 27, 2016 at 09:26:29PM -0700, Guido van Rossum wrote:
>>
>>> We discussed this over dinner at PyCon, some ideas we came up with:
>>>
>>> - Dependent types, harking back to a similar concept in Ada
>>> (https://en.wikibooks.org/wiki/Ada_Programming/Type_System#Derived_types)
>>> which in that language is also spelled with "new".
>>
>> I started to explain this to my non-programmer wife, I got as far as
>> explaining types, and that we need a name for this thing, and she
>> stopped me and said
>>
>> "Please don't tell me this is leading to TypyMcTypeCheck."
>>
>> [...]
>>> - BoatyMcBoatType
>>
>>> The nice thing about "distinguished" is that it's a relatively rare
>>> word so it is easy to remember or look up.
>>
>> I would have thought that being rare, it would be *harder* to remember.
>>
>>
>>> Personally I'm still in favor of Derived type (but I'm more into
>>> ancient programming languages than most folks here). I could also live
>>> with Distinguished Type.
>>
>> I think Derived Type is the nicest of the options. It accurately
>> describes what it is: a type derived from another. And its shorter and
>> easy to both say and write than "Distinguished type" (which sounds like
>> "distinguished gentlemen" -- is it wearing a monocle and a top hat?).
>>
>> "Distinguished" is too vague for my tastes, it might as well be
>> "flibblegubble type". *All* types are distinguished, the type checker
>> has to distinguish int from float from list from str, so to call
>> NewType("userid", int) a "distinguished type" is only to call it a type.
>>
>>
>>
>> --
>> Steve
>> _______________________________________________
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>
>
>
> --
> --Guido van Rossum (python.org/~guido)
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--
--Guido van Rossum (python.org/~guido)
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