[LRUG] Ruby question for a change! Why does this happen...

[Garry Shutler]

foo += []

Is shorthand for:

foo = foo + []

When you think of it like that, it's more obvious that foo has to be a new
variable rather than a call to the existing method.

*Garry Shutler*
@gshutler <http://twitter.com/gshutler>
gshutler.com


On 1 July 2014 10:12, Kenneth Lee <kenfodder at gmail.com> wrote:

> Doing some lazy instantiation and come across this oddity, maybe I'm just
> being dense.
>
> $ irb
>
> irb(main):001:0> def foo
>
> irb(main):002:1>   @bar ||= []
>
> irb(main):003:1> end
>
> => :foo
>
> irb(main):004:0> foo
>
> => []
>
> irb(main):005:0> foo += []
>
> NoMethodError: undefined method `+' for nil:NilClass
>
> from (irb):5
>
> from /Users/ken/.rbenv/versions/2.1.1/bin/irb:11:in `<main>'
>
> irb(main):006:0> foo
>
> => nil
>
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