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Feature #10499

closed

Eliminate implicit magic in Proc.new and Kernel#proc

Added by headius (Charles Nutter) about 7 years ago. Updated about 1 year ago.

Status:
Closed
Priority:
Normal
Target version:
-
[ruby-core:66225]

Description

Proc.new and Kernel#proc have a little known feature: if called without a block, they capture whatever block was passed to the current method.

I propose that this feature should be removed, finally, since it:

  • Doesn't enhance readability (where is this block coming from?)
  • Doesn't reflect any other behavior in Ruby
  • Can lead to bugs (call either without a block accidentally and you aren't sure what you'll get)

I believe this was an implementation artifact in MRI, since the most recently-pushed block would still be on global stacks, which is where the logic for proc and Proc.new looked for it.

All argument syntaxes now support &block, which I believe is the correct way to clearly, explicitly capture the incoming block into an object.

Thoughts?


Related issues

Copied to Ruby master - Feature #15554: warn/error passing a block to a method which never use a blockClosedmatz (Yukihiro Matsumoto)Actions
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