where to find info on ||= operator ?

[Josselin]

I am using

http://www.ruby-doc.org/docs/ProgrammingRuby/

a sa reference manual, but could not find info on that operator (how
to use it..)

tfyl

joss

 

[Martin DeMello]

I am using

http://www.ruby-doc.org/docs/ProgrammingRuby/

a sa reference manual, but could not find info on that operator (how
to use it..)

It's syntax sugar:

foo <operator>= bar

expands to

foo = foo <operator> bar

So a ||= b expands to a = a || b, which (since || is short-circuiting)
means "set a to b if a is nil (or false), otherwise leave it at its
current value.

martin

 

[Farrel Lifson]

I am using

http://www.ruby-doc.org/docs/ProgrammingRuby/

a sa reference manual, but could not find info on that operator (how
to use it..)

tfyl

joss

a ||= b
is equivalent to
a = a || b
If a is nil it will be set to b. If it is not nil it will remain unchanged.

Farrel

 

[Carlos]

I am using

http://www.ruby-doc.org/docs/ProgrammingRuby/

a sa reference manual, but could not find info on that operator (how to
use it..)

tfyl

joss

Hi. Combine this:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UG

with this:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UE

HTH
--

 

[Josselin]

Hi. Combine this:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UG

with this:
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_expressions.html#UE

HTH

thanks a lot.. I should buy a hard-copy .. easier to brwose than a screen....

joss

 

[Josselin]

It's syntax sugar:

foo <operator>= bar

expands to

foo = foo <operator> bar

So a ||= b expands to a = a || b, which (since || is short-circuiting)
means "set a to b if a is nil (or false), otherwise leave it at its
current value.

martin

thansk Martin.. I can read Carlos' link with a good example !

Joss

 

[Josselin]

a ||= b
is equivalent to
a = a || b
If a is nil it will be set to b. If it is not nil it will remain unchanged.

Farrel

Thanks Farrel ... I'll use it now

 

[Wang Dong]

"a ||= b" means "a = b if a != nil"

 

[Justin Collins]

"a ||= b" means "a = b if a != nil"

Mmm, no.

a ||= b is equivalent to:

a = b if a == nil or a == false

or

a = b if a.nil? or not a

or

a = b unless a

or simply

a = a || b

-Justin