Bug #2764

Hash.new inconsistency when initialized with an enumerable

Added by Florent Vaucelle almost 2 years ago. Updated 10 months ago.

[ruby-core:28252]
Status:Rejected Start date:02/20/2010
Priority:Normal Due date:
Assignee:- % Done:

0%
Category:core
Target version:-
ruby -v:ruby 1.8.7 (2009-04-08 patchlevel 160) [i686-darwin9]

Description

When initializing a Hash with an enumerable as default value, Hash.new(obj) and Hash.new(&block) have different behaviours.

Example:
h = Hash.new([])
h[10] << 20
h #=> {}

h = Hash.new { |hash, key| hash[key] = [] }
hash[10] << 20
h #=> {10=>20}

The example similar when using a String instead of an Array as default value.

History

#1
Updated by Marc-Andre Lafortune almost 2 years ago

  • Category set to core
  • Status changed from Open to Rejected
This is by design.

Note that the behavior is actually different for all types of objects, even immediates

h = Hash.new(42)
h[:foo]  # ==> 42
h.keys   # ==> []

h = Hash.new { |hash, key| hash[key] = 42 }
h[:foo]  # ==> 42
h.keys   # ==> [:foo]

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