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comp.lang.ruby

Boolean Operators

Mark Dodwell

3/28/2008 11:22:00 PM

Quick question:

I know that the 'and' and 'or' operators in ruby have the same
precedence, and '&&' has a higher one than '||' - but is there a best
practise for which one to use when precedence isn't important?

Thanks,

~ Mark
--
Posted via http://www.ruby-....
3 Answers

Robert Klemme

3/29/2008 4:55:00 PM

0

On 29.03.2008 00:22, Mark Dodwell wrote:
> I know that the 'and' and 'or' operators in ruby have the same
> precedence, and '&&' has a higher one than '||' - but is there a best
> practise for which one to use when precedence isn't important?

I usually use && and || because they visually stand out better than
"and" and "or" and can be used with assignments (higher precedence than
"="). I use "and" and "or" rather seldom mostly when chaining commands
as in

foo = doit() and puts foo

YMMV

Kind regards

robert

Rick DeNatale

3/30/2008 12:17:00 PM

0

On 3/29/08, Robert Klemme <shortcutter@googlemail.com> wrote:
> I use "and" and "or" rather seldom mostly when chaining commands
> as in
>
> foo = doit() and puts foo

Keeping in mind that using && instead of and here has quite a
different result, even after adjusting the syntax of the puts call:

irb(main):001:0> a = 1 and puts "foo"
foo
=> nil
irb(main):002:0> a
=> 1
irb(main):003:0> a = 1 && puts "foo"
SyntaxError: compile error
(irb):3: syntax error, unexpected tSTRING_BEG, expecting kDO or '{' or '('
a = 1 && puts "foo"
^
from (irb):3
irb(main):004:0> a = 1 && puts("foo")
foo
=> nil
irb(main):005:0> a
=> nil

I don't know that I've ever used 'and' since being bitten by the
relative precedence of = and 'and' in a rails app I inherited and was
extending.

I also don't believe that I'd personally use
a = 1 and puts "foo"

rather than splitting it into two lines, perhaps replacing the and
with a semi-colon or otherwise steppng back and micro-refactoring the
code to make it clearer.

But I could be wrong.
--
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denh...

Robert Klemme

3/30/2008 12:30:00 PM

0

On 30.03.2008 14:16, Rick DeNatale wrote:
> On 3/29/08, Robert Klemme <shortcutter@googlemail.com> wrote:
>> I use "and" and "or" rather seldom mostly when chaining commands
>> as in
>>
>> foo = doit() and puts foo
>
> Keeping in mind that using && instead of and here has quite a
> different result, even after adjusting the syntax of the puts call:

Which is the precise reason why I would use "and" in this case. Note
that I wrote "seldom" so this is not a too frequent idiom I employ.

> rather than splitting it into two lines, perhaps replacing the and
> with a semi-colon or otherwise steppng back and micro-refactoring the
> code to make it clearer.
>
> But I could be wrong.

I don't think so. This is also a question of personal style and I don't
find anything wrong with your approach.

Kind regards

robert