Powershell: Feature Request: Allow to change default variable scope

[Tragen]

Currently, the default variable scope allows variables to be accessed in child scopes.
I always had a lot of problems with this in bigger scripts.
It would be nice to have an option, e.g. at the beginning of a script, which tells PS
that the default scope should be private for this script.

[mburszley]

That is the purpose of declaring your variables with scope, .e.g, $private:myVar

[vexx32]

Correct. I believe the request is to have a way in the script to set such a scope to be the _default_ for all variables in that scope, so that when creating an unscoped variable it is automatically assigned the private scope.

[Tragen]

Yes, exactly. When you have very long scripts, it's very ugly to prefix all variables with private

[mklement0]

PowerShell's dynamic scoping is a problem in other areas too, notably with not wanting Set-StrictMode settings to apply to child scopes ((third-party) code is often written with the assumption that no strict mode is in effect, and one going into effect in the caller's scope can break the code - see the (languishing) lexical strict-mode RFC at https://github.com/PowerShell/PowerShell-RFC/issues/7

For more robust code, lexically scoped variables, or their emulation with the $private: scope modifier, but _without the latter's ceremony_ would indeed be helpful, but requires an _opt-in_ mechanism so as not to break backward compatibility.

Conceivably, a new using statement could using be introduced that makes all local variables private _by default_, along the lines of using private variables; however, this implies that the option is only available at the _file_ level, not to individual functions. [_update_: also, the effect would have to be lexically scoped, which the current using statements are _not_].

[vexx32]

Not a bad suggestion, @mklement0. For myself, I was imagining introducing a preference variable; e.g., $PSDefaultVariableScope = 'Private'

[mklement0]

The problem with preference variables is again their dynamic scoping - child scopes that weren't written with all-private variables in mind could break.

I suggested using under the mistaken assumption was that they are lexically scoped to the enclosing script / script module, but as it turns out they're _not_, not even in the using namespace case.

I suppose something like $private:PSDefaultVariableScope = 'Private' would work in a given scope, come to think of it, but that is obscure.

[Tragen]

This isn't answered yet

[msftbot[bot]]

This issue has been marked as answered and has not had any activity for 1 day. It has been closed for housekeeping purposes.