[issue36764] Types module doesn't have a type for _abc_data

[Serhiy Storchaka]

Serhiy Storchaka  added the comment:

I concur with Inada. This is a deep implementation detail. Instances of this 
type are not even exposed to users. And the types module should not contain all 
types used in CPython.

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nosy: +serhiy.storchaka
resolution:  -> rejected
stage: patch review -> resolved
status: open -> closed

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[issue36764] Types module doesn't have a type for _abc_data

[Inada Naoki]

Inada Naoki  added the comment:

You didn't explain why people not only you need it.
"Could you elaborate?"

Unless clear use cases, I'm strong -1 on adding it in typing module.

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[issue36764] Types module doesn't have a type for _abc_data

[Batuhan]

Batuhan  added the comment:

We can try to obtain the type of ABCData and if we can't (if py_abc is
used) we can set ABCData to NotImplemented.

On Wed, May 1, 2019, 2:56 PM Batuhan  wrote:

>
> Batuhan  added the comment:
>
> It is based on default behavior of cpython. It tries to import _abc first
> instead of _py_abc and this type targets c implementation.
>
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[issue36764] Types module doesn't have a type for _abc_data

[Batuhan]

Batuhan  added the comment:

It is based on default behavior of cpython. It tries to import _abc first 
instead of _py_abc and this type targets c implementation.

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[issue36764] Types module doesn't have a type for _abc_data

[Inada Naoki]

Inada Naoki  added the comment:

> I'm using it both for comparisons which needed to build an abstract base 
> class and typing. Currently there are 2 ways, i need to create a dummy abc 
> and put type() calls everywhere or i need to set a constant to my module and 
> _abc_data is totally irrelevant with this. I dont think users want that.

It doesn't make sense to me.  Could you elaborate?


> Abstract base classes can be called a core part of python too

abc is core part.  But note that _py_abc can be used instead of _abc.
_abc_data is used only when _abc is used as backend of abc.
At least, your pull request doesn't work correctly when _py_abc is used.


>  and when someone needs to obtain type of the struct that holds state of ABCs 
> it shouldnt be hard, types module should expose it.

I think it is bad idea and we don't support such usage officially at all.
Such code doesn't work when _py_abc is used.

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[issue36764] Types module doesn't have a type for _abc_data

[Batuhan]

Batuhan  added the comment:

> I still don't understand why you need _abc_data.
I'm using it both for comparisons which needed to build an abstract base class 
and typing. Currently there are 2 ways, i need to create a dummy abc and put 
type() calls everywhere or i need to set a constant to my module and _abc_data 
is totally irrelevant with this. I dont think users want that.

> On the other hand, _abc_data is implementation detail of extension module, 
> not interpreter.
Abstract base classes can be called a core part of python too and when someone 
needs to obtain type of the struct that holds state of ABCs it shouldnt be 
hard, types module should expose it.

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[issue36764] Types module doesn't have a type for _abc_data

[Inada Naoki]

Inada Naoki  added the comment:

> I'm working on a project that is a custom byte code interpreter for some
extended types.  I needed ABCData there

I still don't understand why you need _abc_data.


> Isn't types module exposing some types that are implementation detail such as 
> cells?

cell object is implementation detail of CPython core.
While other Python implementations will not have it, it is long lived in 
CPython and it is stable.

On the other hand, _abc_data is implementation detail of extension module, not 
interpreter.

For example, _json.Encoder is not exposed in types module.
If it is really needed, type of _abc_data can be exposed via _abc module.
But I prefer keep internal data opaque unless there are reasonable reason.

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[issue36764] Types module doesn't have a type for _abc_data

[Batuhan]

Batuhan  added the comment:

I'm working on a project that is a custom byte code interpreter for some
extended types. I needed ABCData there and i thought types module already
has that, but i was wrong so i added.

Isn't types module exposing some types that are implementation detail such
as cells?

On Wed, May 1, 2019, 12:17 PM Inada Naoki  wrote:

>
> Inada Naoki  added the comment:
>
> It's implementation detail of abc.  I don't want expose it in public.
> (Note that we maintain pure Python version of abc module too.)
>
> Why you need it in types module?
> I don't think all types exposed via types module.  Only useful types
> should be exposed.
>
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> nosy: +inada.naoki
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[issue36764] Types module doesn't have a type for _abc_data

[Inada Naoki]

Inada Naoki  added the comment:

It's implementation detail of abc.  I don't want expose it in public.
(Note that we maintain pure Python version of abc module too.)

Why you need it in types module?
I don't think all types exposed via types module.  Only useful types should be 
exposed.

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nosy: +inada.naoki

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[issue36764] Types module doesn't have a type for _abc_data

[SilentGhost]

Change by SilentGhost :


--
components: +Library (Lib)
nosy: +yselivanov
type:  -> enhancement
versions: +Python 3.8

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[issue36764] Types module doesn't have a type for _abc_data

[Roundup Robot]

Change by Roundup Robot :


--
keywords: +patch
pull_requests: +12954
stage:  -> patch review

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[issue36764] Types module doesn't have a type for _abc_data

[Batuhan]

New submission from Batuhan :

Types module doesn't have a type for _abc_data

--
messages: 341180
nosy: isidentical
priority: normal
severity: normal
status: open
title: Types module doesn't have a type for _abc_data

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