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Ruby

Alphonse Cuccurullo
Alphonse Cuccurullo
2,513 Points
Posted by Alphonse Cuccurullo
Alphonse Cuccurullo
2,513 Points

Can someone explain to me the purpose of conditional assignments?

Can someone give me a useful scenario where conditional assignments are helpful?

1 Answer

Daniel Crews
Daniel Crews
14,008 Points
Daniel Crews
Daniel Crews
14,008 Points

a ||=b is 'almost' equivalent to a || a = b

If a is falsy (false, nil or undefined) it will set a to the value of b, otherwise it will leave a as is and the right side isn't evaluated.

For example:

a = nil

b = 20

a ||= b

a # => 20

Why? It sets 'a' to a default value if a has no value. Think of it as a || a = "default". Practical example, instantiate a new empty hash b ||= {}, or array c ||= []

It is ALMOST equivalent to a || a = b because a || a=b will throw an error if a is undefined.