Ruby equivalent to JS

Question

Is there an expression in Ruby equivalent to JavaScript's for:

myHash[id] = myHash[id] || {};

This is usually used when trying to append an array or hash to an existing one but we don't know if it was already created or is the first iteration.

Don't know Ruby, but wouldn't just it's logical OR work? Does it return a boolean value or the first truthy value? — Carcigenicate
– Carcigenicate, Commented Mar 7, 2017 at 18:43
Please do not use salutations like "hi", valedictions ("thanks!") or signatures. Stack Overflow is not a discussion list, it's an online reference. Also, grammar, spelling and punctuation are all significant. — the Tin Man
– the Tin Man, Commented Mar 7, 2017 at 22:56

the Tin Man · Accepted Answer · 2017-03-07 22:44:59Z

2

In Ruby, this code actually works the same as in JavaScript:

myHash[id] = myHash[id] || {}

That being said, the more eloquent way of doing it is:

myHash[id] ||= {}

edited Mar 7, 2017 at 22:44

the Tin Man

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answered Mar 7, 2017 at 18:44

eiko

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the Tin Man · Accepted Answer · 2017-03-07 22:58:00Z

0

While these are equivalent:

my_hash[:id] = my_hash[:id] || {} 
my_hash[:id] ||= {}

You'll find this useful:

require 'fruity'

my_hash = {}

compare do
  test1 { my_hash[:id] = my_hash[:id] || {} }
  test2 { my_hash[:id] ||= {} }
end

# >> Running each test 32768 times. Test will take about 1 second.
# >> test2 is faster than test1 by 2x ± 0.1

Between the two, the second, test2, is idiomatic Ruby, so, while the difference in speed is slight, it adds up. It's also the Ruby way.

edited Mar 7, 2017 at 22:58

answered Mar 7, 2017 at 22:49

the Tin Man

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