Hi people,

Did I dream about an opeartor |=?

I can't find any reference to it in the online docs, yet I think I've seen
it in some samples.

What does it do?

TIA


--
Fernando Cacciola
SciSoft
http://fcacciola.50webs.com

> Did I dream about an opeartor |=?
> I can't find any reference to it in the online docs, yet I think I've
> seen it in some samples.
> What does it do?

It sets a value if the variable does not have one, like:

>> foo ||= :bar
=> :bar
>> foo ||= :xyz
=> :bar

Regards,

--
Eustáquio "TaQ" Rangel
http://eustaquiorangel.com

"Simplicity is the ultimate sophistication."
Leonardo da Vinci

On Nov 6, 2007, at 5:58 AM, Fernando Cacciola wrote:

> Hi people,
>
> Did I dream about an opeartor |=?
>
> I can't find any reference to it in the online docs, yet I think
> I've seen it in some samples.
>
> What does it do?
>
> TIA
>
It's not exactly an operator itself, it is syntactic sugar.
You can find it well discussed in the archives.
|= means David A. Black.

Fernando Cacciola wrote:
> Hi people,
>
> Did I dream about an opeartor |=?
>
> I can't find any reference to it in the online docs, yet I think I've
> seen it in some samples.
>
> What does it do?

I can see it in the pickaxe chm, under The Ruby Language => Expressions
=> Operator Expressions.

I guess it's the same as

leftval = leftval | rightval

that is, binary OR.

mortee

2007/11/6, Fernando Cacciola <fernando.cacciola@gmail.com>:
> Hi people,
>
> Did I dream about an opeartor |=?
>

It exists

>
> What does it do?
>

It works for integers like the binary OR:
foo = 3 | 4 # result: 7
bar = 3
bar |= 4 # result: 7

Did you mean ||=? It is used to set default values if a variable is
not definied yet.
foo = 3
foo ||= 4 # foo doesn't change
baz ||= 4 # baz is 4 if it wasn't defined before

Regards, Thomas

Paul Danese wrote:
> You might be thinking about ||=

Ha, ya, that one...

Thank you.

> I believe a |= b "ORs" the bits in a and b and assigns them to a

Oh, just like in C.... who would have thought (just kiding

Best

Fernando Cacciola
SciSoft
http://fcacciola.50webs.com

Hi,

On Tue, 2007-11-06 at 21:21 +0900, Eustáquio 'TaQ' Rangel wrote:
> > Did I dream about an opeartor |=?
> It sets a value if the variable does not have one, like:
>
> >> foo ||= :bar
> => :bar
> >> foo ||= :xyz
> => :bar

Please take care not to confuse ||= with |=.

||= does as you say. |= is an assignment bitwise OR.

Arlen

> operator |=
> Posted by Fernando Cacciola (Guest) on 06.11.2007 12:59
>
> Hi people,
>
> Did I dream about an opeartor |=?
>
> I can't find any reference to it in the online docs, yet I think I've seen
> it in some samples.
>
> What does it do?

|= can also be used with arrays.

shopping_list = ['peanut butter', 'grape jelly', 'whole wheat bread']
shopping_list |= ['peanut butter', 'sugar']
p shopping_list #=> ['peanut butter', 'grape jelly', 'whole wheat
bread', 'sugar']

(cf. http://rubysnips.com/add-to-array-if )

Cheers,

j. k.
--
Posted via http://www.ruby-forum.com/.

On 11/6/07, Paul Danese <pdanese@rib-x.com> wrote:
> You might be thinking about ||=
> ||= assigns a value to a variable if the variable is nil

To be precise, it assigns a value to a variable which is either
undefined, nil or false.
--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

On 11/6/07, John Joyce <dangerwillrobinsondanger@gmail.com> wrote:


> |= means David A. Black.


Hmmmm, I wonder if David knew that! <G>


--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/