Hash behavior query

[Abhisek Datta]

irb(main):001:0> d = [1,2,3,4]
=> [1, 2, 3, 4]
irb(main):002:0> h = Hash.new
=> {}
irb(main):003:0> h[d] = "hello"
=> "hello"
irb(main):004:0> h
=> {[1, 2, 3, 4]=>"hello"}
irb(main):005:0> h[d]
=> "hello"
irb(main):006:0> d.push(5)
=> [1, 2, 3, 4, 5]
irb(main):007:0> h[d]
=> nil
irb(main):008:0> h
=> {[1, 2, 3, 4, 5]=>"hello"}
irb(main):009:0> d
=> [1, 2, 3, 4, 5]
irb(main):010:0> h[d]
=> nil
irb(main):011:0> h.rehash
=> {[1, 2, 3, 4, 5]=>"hello"}
irb(main):012:0> h[d]
=> "hello"
irb(main):013:0>


Is this expected or a bug?

-abhisek

 

[dblack]

Hi --

irb(main):001:0> d = [1,2,3,4]
=> [1, 2, 3, 4]
irb(main):002:0> h = Hash.new
=> {}
irb(main):003:0> h[d] = "hello"
=> "hello"
irb(main):004:0> h
=> {[1, 2, 3, 4]=>"hello"}
irb(main):005:0> h[d]
=> "hello"
irb(main):006:0> d.push(5)
=> [1, 2, 3, 4, 5]
irb(main):007:0> h[d]
=> nil
irb(main):008:0> h
=> {[1, 2, 3, 4, 5]=>"hello"}
irb(main):009:0> d
=> [1, 2, 3, 4, 5]
irb(main):010:0> h[d]
=> nil
irb(main):011:0> h.rehash
=> {[1, 2, 3, 4, 5]=>"hello"}
irb(main):012:0> h[d]
=> "hello"
irb(main):013:0>


Is this expected or a bug?

You've pretty much reproduced the documented example from the source
code, so I'd say it's expected


David

--
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
(See what readers are saying! http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)

 

[Robert Dober]

Hi --

irb(main):001:0> d = [1,2,3,4]
=> [1, 2, 3, 4]
irb(main):002:0> h = Hash.new
=> {}
irb(main):003:0> h[d] = "hello"
=> "hello"
irb(main):004:0> h
=> {[1, 2, 3, 4]=>"hello"}
irb(main):005:0> h[d]
=> "hello"
irb(main):006:0> d.push(5)
=> [1, 2, 3, 4, 5]
irb(main):007:0> h[d]
=> nil
irb(main):008:0> h
=> {[1, 2, 3, 4, 5]=>"hello"}
irb(main):009:0> d
=> [1, 2, 3, 4, 5]
irb(main):010:0> h[d]
=> nil
irb(main):011:0> h.rehash
=> {[1, 2, 3, 4, 5]=>"hello"}
irb(main):012:0> h[d]
=> "hello"
irb(main):013:0>


Is this expected or a bug?

You've pretty much reproduced the documented example from the source
code, so I'd say it's expected

... and furthermore was there not somebody asking whether to prefer
Strings or Symbols as hash keys.
I think the example above gives you some hints, -- sometimes Strings
are still a good choice, but only sometimes.

Cheers
Robert