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[Python-Dev] Please reject or postpone PEP 526

Koos Zevenhoven k7hoven at gmail.com
Sun Sep 4 08:08:28 EDT 2016 
On Sun, Sep 4, 2016 at 1:52 PM, Mark Shannon <mark at hotpy.org> wrote:
[...]
>
> The key difference is in placement.
> PEP 484 style
> variable = value # annotation
>
> Which reads to me as if the annotation refers to the value.
> PEP 526
> variable: annotation = value
>
> Which reads very much as if the annotation refers to the variable.
> That is a change in terms of semantics and a change for the worse, in terms
> of expressibility.
>

You have probably noticed this already, but in the semantics which I
have now explained more precisely on python-ideas

https://mail.python.org/pipermail/python-ideas/2016-September/042076.html

an annotation like

variable: annotation = value

is a little closer to an expression annotation. I.e. it does not say
that 'variable' should *always* have the type given by 'annotation'.

-- Koos

>
> Cheers,
> Mark.
>
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