Backport #9270: Array#to_h should not ignore badly formed elements

• Status: Closed
• Assignee: naruse (Yui NARUSE)

[marcandre (Marc-Andre Lafortune)]

The upcoming Array#to_h feature currently ignores elements that are not 2-elements arrays. Array#to_h could instead raise an error on those elements. I argued otherwise before, but maybe that would be safer.

One reason I think I was wrong is that current form could encourage code like:

enum.map{|x| [x.foo, x.bar] if x.baz? }.to_h

using the fact that any nil will be ignored. I'm not sure that it's a good idea.

It would probably be safer to raise an Exception for elements that are not a key-value pair. It also satisfies fail-early principle.

@sawa (Tsuyoshi Sawada) agrees with this.
@matz (Yukihiro Matsumoto) agrees with the change.

Since this feature has not already been released in an official version, changing this behavior now would not cause any incompatibility and there should be no risk of regression. Changing this feature after the official 2.1 release would be more problematic as it could cause incompatibilities.

Yui, could you please confirm that there is no problem on your end for me to commit the following patch: https://github.com/marcandre/ruby/compare/to_h_raise

[naruse (Yui NARUSE)]

OK, could you commit it?
I'll backport it to ruby_2_1 branch.

[marcandre (Marc-Andre Lafortune)]

• Tracker changed from Feature to Backport
• Project changed from Ruby master to Backport21
• Category deleted (core)
• Target version deleted (2.1.0)

Great, thanks.

Committed as r44354

[naruse (Yui NARUSE)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r44361.
Marc-Andre, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

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merge revision(s) 44354: [Backport #9270]

* array.c: Have to_h raise on elements that are not key-value pairs
  [#9239]

* enum.c: ditto