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Add noscope macro to make try blocks evaluate in the local scope#39217

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IanButterworth:ib/noscope_try
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Add noscope macro to make try blocks evaluate in the local scope#39217
IanButterworth wants to merge 1 commit intoJuliaLang:masterfrom
IanButterworth:ib/noscope_try

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@IanButterworth IanButterworth commented Jan 12, 2021 •
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It could be generally useful to evaluate a try in the local scope, as is the case in #39138

Based on a suggestion by @vtjnash this adds @noscope for making try blocks evaluate in the local scope

julia> x
ERROR: UndefVarError: x not defined

julia> try
            x = 1
            error()
        catch err
            display(err)
        finally
            println("finally")
        end
ErrorException()
finally

julia> x
ERROR: UndefVarError: x not defined

julia> @noscope try
            x = 1
            error()
        catch err
            display(err)
        finally
            println("finally")
        end
ErrorException()
finally

julia> x
1

If this is supported, there may be a better place for the code and tests to sit?

@vtjnash vtjnash added the triage This should be discussed on a triage call label Jan 12, 2021
fredrikekre
fredrikekre reviewed Jan 12, 2021
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base/essentials.jl
1
```
"""
macro noscope(ex)
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@fredrikekre fredrikekre Jan 12, 2021

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Maybe

Suggested change
macro noscope(ex)
macro noscope360(ex)

?

IanButterworth
IanButterworth commented Jan 13, 2021
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base/essentials.jl
Expr(:trycatch,
:($(esc(ex.args[1]))),
quote
begin
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@IanButterworth IanButterworth Jan 13, 2021 •
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Actually, I think this and all the finally and catch blocks should still be scoped

Suggested change
begin
let

@IanButterworth IanButterworth mentioned this pull request Jan 15, 2021
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f0103
f0103 approved these changes Feb 10, 2021
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@JeffBezanson
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JeffBezanson commented Feb 11, 2021

From triage:

  • Basically yes
  • Would be nice to implement it properly in the front-end, and handle all kinds of scope-introducing blocks
  • We probably still want the variable in catch e to be local to its block. Similarly for @noscope let x = ..., the x should still be local, but nothing inside should introduce new variables to the scope. That will require some surgery in the scope pass.

@StefanKarpinski StefanKarpinski added feature Indicates new feature / enhancement requests compiler:lowering Syntax lowering (compiler front end, 2nd stage) and removed triage This should be discussed on a triage call labels Apr 29, 2021
This was referenced Aug 18, 2021
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@IanButterworth IanButterworth mentioned this pull request Jan 28, 2023
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@simonbyrne simonbyrne mentioned this pull request Feb 9, 2023
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IanButterworth commented Dec 7, 2023

With #48434 being open and it being unlikely that I'd take this forward, I'll close this

@IanButterworth IanButterworth deleted the ib/noscope_try branch December 7, 2023 18:24
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@IanButterworth @JeffBezanson @oOosys @fredrikekre @f0103 @StefanKarpinski @vtjnash