Why doesn't assigning a variable to an array yield expected results in Ruby?

Question

Using IRB, I tested the following:

C:\Pickaxe>irb
irb(main):001:0> list_of_strings = %w{ a list of strings in an array }
=> ["a", "list", "of", "strings", "in", "an", "array"]
irb(main):002:0> a, b, c = list_of_strings
=> ["a", "list", "of", "strings", "in", "an", "array"]
irb(main):003:0> a
=> "a"
irb(main):004:0> b
=> "list"
irb(main):005:0> c
=> "of"
irb(main):006:0>

In the other languages I've developed in setting a, b, c = d sets the values of a, b and c to equal d in its entirety. Here they are set to successive elements in the array.

I don't understand how or why this works. Could someone shed light on the issue?

Ahh, thank you Squiguy. Is there a way I could assign the values of a, b, and c to the whole array without having to do it on multiple lines? — Senjai
– Senjai, Commented May 14, 2013 at 22:44
@squiguy: Destructuring bind in Ruby works pretty much exactly how it works in every other language. Not sure what's so different about that. — Jörg W Mittag
– Jörg W Mittag, Commented May 15, 2013 at 0:31
@squiguy, "I mean the language always brags that it does 'what makes sense to the programmer.'" Matz, says "The principle of least surprise means principle of least my surprise. And it means the principle of least surprise after you learn Ruby very well." Personally, after many other languages, I find Ruby to be very intuitive when I stop to think about what I'm doing. Being human I sometimes don't do that, which is when I am surprised. — the Tin Man
– the Tin Man, Commented May 15, 2013 at 1:35

the Tin Man · Accepted Answer · 2013-05-15 01:44:38Z

1

That's just how array assignment works in Ruby. It's trying to be clever, a little, by assigning each indexed item of the array to that variable on the left-hand side of the assignment =

edited May 15, 2013 at 1:44

the Tin Man

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answered May 14, 2013 at 22:40

Alex Mcp

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1 Comment

the Tin Man Over a year ago

I'm not sure why this would be surprising. Perl does the same thing, and it's been around for years and years, and it's very much a mainstream language.

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