[Python-ideas] PEP draft: context variables

[Guido van Rossum]

On Tue, Sep 5, 2017 at 7:42 AM, Neil Girdhar <mistersheik at gmail.com> wrote:

> I think you really should add a context manager to PEP 550 since it is
> better than calling "set", which leaks state.  Nathaniel is right that you
> need set to support legacy numpy methods like seterr.  Had there been a way
> of setting context variables using a context manager, then numpy would only
> have had to implement the "errstate" context manager on top of it.  There
> would have been no need for seterr, which leaks state between code blocks
> and is error-prone.
>

There is nothing in current Python to prevent numpy to use a context
manager for seterr; it's easy enough to write your own context manager that
saves and restores thread-local state (decimal shows how). In fact with PEP
550 it's so easy that it's really not necessary for the PEP to define this
as a separate API -- whoever needs it can just write their own.

-- 
--Guido van Rossum (python.org/~guido)
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