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1. JelleZijlstra

   added

   type-featureA feature request or enhancementA feature request or enhancement

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   on Feb 28, 2024
2. sobolevn

   added a commit that references this issue on Feb 28, 2024

   pythongh-116023: Add `show_empty=True` to `ast.dump`

   217c2b1
3. sobolevn

   added a commit that references this issue on Apr 24, 2024

   gh-116023: Add `show_empty=False` to `ast.dump` (#116037)

   ...

   692e902
4. sobolevn

   closed this as completedon Apr 24, 2024
5. JelleZijlstra commented on Apr 28, 2024

   

   JelleZijlstra

   on Apr 28, 2024

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   I noticed that the representation on an empty ast.Tuple changed from Tuple(elts=[], ctx=Load()) to Tuple(ctx=Load()), and same for lists and dicts:

   >>> ast.dump(ast.parse('[]'))
   'Module(body=[Expr(value=List(ctx=Load()))])'
   >>> ast.dump(ast.parse('{}'))
   'Module(body=[Expr(value=Dict())])'
   >>> ast.dump(ast.parse('()'))
   'Module(body=[Expr(value=Tuple(ctx=Load()))])'
   

   I think this is fine; it matches the constructor and it is analogous to how list(), dict(), and tuple() work. However, I thought I'd flag it in case others think these nodes should be special-cased.
6. AlexWaygood commented on Apr 28, 2024

   

   AlexWaygood

   on Apr 28, 2024

   Last edited by AlexWaygood

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   >>> ast.dump(ast.parse('[]'))
   'Module(body=[Expr(value=List(ctx=Load()))])'
   >>> ast.dump(ast.parse('{}'))
   'Module(body=[Expr(value=Dict())])'
   >>> ast.dump(ast.parse('()'))
   'Module(body=[Expr(value=Tuple(ctx=Load()))])'

   Why does the repr for ast.Dict() not include ctx=Load() in it, when the reprs for Tuple and List do?
7. AlexWaygood commented on Apr 28, 2024

   

   AlexWaygood

   on Apr 28, 2024

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   Why does the repr for ast.Dict() not include ctx=Load() in it, when the reprs for Tuple and List do?

   I see that the same thing happens on Python 3.12, so this definitely isn't a regression... but I'd still be curious if anybody knows why this is different for the different nodes!
8. JelleZijlstra commented on Apr 28, 2024

   

   JelleZijlstra

   on Apr 28, 2024

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   It's because ast.Dict can't appear on the left-hand side of an assignment.

   >>> [x] = (3,)
   >>> (x,) = (3,)
   >>> {x: x} = {3: 3}
     File "<stdin>", line 1
       {x: x} = {3: 3}
       ^^^^^^
   SyntaxError: cannot assign to dict literal here. Maybe you meant '==' instead of '='?
   

   I was thinking of whether we'd also want to default the ctx parameter of these and other nodes to Load(), but that's for another day.

   ❤️React with ❤️1Reacted by Alex Waygood