Add inline variable refactor #2504

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1. vinistock

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   enhancementNew feature or requestNew feature or request

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   on Aug 28, 2024
2. ttilberg commented on Sep 20, 2024

   

   ttilberg

   on Sep 20, 2024

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   I was reading through this issue, and wanted to note that the resulting expression may need to have parenthesis in order to keep order of operations good. I'm not sure if it would be possible to calculate that it's not needed. Some examples counter to the example in the issue:

   # Subtraction before multiplication
   # BEFORE
   def foo
     a = 5 - 10
     puts a  # => -5
     b = a * 5  # => -25
   end
   
   # Without ()
   def foo
     puts 5 - 10 # => -5
     b = 5 - 10 * 5 # => **-45**
   end
   
   # With ()
   def foo
     puts (5 - 10) # => -5
     b = (5 - 10) * 5 # => **-25**
   end
   

   I can't think of an example for this other thought quick enough, but I suspect there would be issues with certain method calling instances as well, akin to what you see with 1..10.map vs (1..10).map... you know, all those classic cases where you end up needing parens afterall.

   I just wanted to highlight this concern as I feel like this refactoring tool could create some easy-to-miss bugs if it doesn't wrap the expression in parens.
3. ttilberg commented on Sep 20, 2024

   

   ttilberg

   on Sep 20, 2024

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   Maybe there should be a check for "does the replacement candidate, or replacement targets include any method calls" in the ast? And if so, we should use parens? This may be naïve, but it seems like that's where things can get sticky.
4. vinistock commented on Sep 20, 2024

   

   vinistock

   on Sep 20, 2024

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   That's a really good point. Maybe the implementation should check if the target of the inlining is a unary/math expression and then enforce parenthesis in those cases.
5. andyw8

   added

   rubyconf-hackdays

   on Oct 21, 2024
6. vinistock

   removed

   rubyconf-hackday

   on Feb 11, 2025
7. IslamElsayed commented on Oct 28, 2026

   

   IslamElsayed

   on Oct 28, 2026

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   I'd like to pick this up. The plan is an "Inline variable" code action, offered when the cursor is on a local variable's assignment or on one of its reads. It replaces every read in the same scope with the assigned expression and removes the assignment, wrapping the expression in parentheses when it's a binary or unary expression, as you suggested above.

   I'd leave the action out when the variable is reassigned in the scope, and when the value contains a method call and is read more than once, since inlining would change how often it runs. Does that match what you had in mind?

   (I use AI assistance when working on patches, and I check and test everything before submitting.)