[Python-Dev] PEP 567 v2 (original) (raw)

Victor Stinner victor.stinner at gmail.com
Thu Dec 28 18:48:00 EST 2017

NLe 28 déc. 2017 11:20 AM, "Nathaniel Smith" <njs at pobox.com> a écrit :

On Thu, Dec 28, 2017 at 1:51 AM, Victor Stinner <victor.stinner at gmail.com> wrote:

var = ContextVar('var', default=42)

and: var = ContextVar('var') var.set (42) behaves the same, no?

No, they're different. The second sets the value in the current context. The first sets the value in all contexts that currently exist, and all empty contexts created in the future.

Oh, that's an important information. In this case, "default" is the best name.

The PEP may be more explicit about the effect on all contexts. Proposition of documentation:

"The optional default parameter is the default value in all contexts. If the variable is not set in the current context, it is returned by by context[var_name] and by var.get(), when get() is called without the default parameter."

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