# N00b if condition quest

I’m sure theres a way, so how does one do:

if (a = b or a = c or a = d or a = f)

in a shorter, easier to view

if (a = (b c d or f)) kind of way?

Hi –

On Fri, 27 Jul 2007, Brett B. wrote:

I’m sure theres a way, so how does one do:

if (a = b or a = c or a = d or a = f)

in a shorter, easier to view

if (a = (b c d or f)) kind of way?

You mean == rather than = , but in any case, try this:

if [b,c,d,f].include?(a)

David

== indeed.

That’s gorgeous, thanks! Works brilliantly.

On Jul 26, 4:22 pm, Brett B. [email protected] wrote:

I’m sure theres a way, so how does one do:

if (a = b or a = c or a = d or a = f)

in a shorter, easier to view

if (a = (b c d or f)) kind of way?

case n
when 1,2,3: puts ‘1-3’
when 4…6: puts ‘4-6’
else puts ‘other’
end

You can, of course, use variables instead of literals, ala

case a
when b, c, d, f

end

Hi –

On Fri, 27 Jul 2007, Phrogz wrote:

when 1,2,3: puts ‘1-3’
when 4…6: puts ‘4-6’
else puts ‘other’
end

You can, of course, use variables instead of literals, ala

case a
when b, c, d, f

end

That doesn’t test for equality, though.

David

On 7/27/07, [email protected] [email protected] wrote:

if (a = (b c d or f)) kind of way?

You mean == rather than = , but in any case, try this:

if [b,c,d,f].include?(a)

You are right for sure that OP meant ==, but let us answer the
original question too

a = [b,c,d,e,f].compact.first

Robert

Robert D. wrote:

You are right for sure that OP meant ==, but let us answer the
original question too

a = [b,c,d,e,f].compact.first

Not quite.

b=c=d=false
e=f = 99
a1 = [b,c,d,e,f].compact.first
a2=b or a2=c or a2=d or a2=e or a2=f
puts a1, a2

a1 is false and a2 is 99

Ian

On Behalf Of Brett B.:

# == indeed.

also take a look at #any? and #all?

they come in handy in situations like,

if a < b or a < c or a < d

if a > b and a > c and a > d

sometimes, you may want a reverse to #include? behavior so that you’d
like to emphasize first the element as compared to the collection.
something like,

a.in?[b,c,d,f]

kind regards -botp

On Jul 26, 5:38 pm, [email protected] wrote:

else puts ‘other’
end
That doesn’t test for equality, though.

An important semantic point. For example:

case 1…3
when 1…3: puts ‘yay!’
else puts ‘boo’
end

results in “boo”, because (1…3) === (1…3) #=> false

Still, as the docs for Object#=== say:
“For class Object, effectively the same as calling #==, but typically
overridden by descendants to provide meaningful semantics in case
statements.”

Numbers, strings, arrays, hashes, booleans…all these treat === as
==. I’m not arguing that they should be treated the same, or that we
should sweep the difference under the rug. I’m simply suggesting that
if you know the difference between #== and #===, particularly on the
objects that you place in your case statements, then under many
circumstances you can use a case statement as a convenience for
checking equality on many objects at once.

(Not that there was anything wrong with your initial suggestion of
Array#any?, of course.)

On Jul 27, 4:43 am, “Robert D.” [email protected] wrote:

On 7/27/07, [email protected] [email protected] wrote:

On Fri, 27 Jul 2007, Brett B. wrote:

if (a = b or a = c or a = d or a = f)
You mean == rather than = , but in any case, try this:
You are right for sure that OP meant ==, but let us answer the
original question too

a = [b,c,d,e,f].compact.first

Your solution forces the evaluation of b/c/d/e/f, which the OP’s does
not (thanks to the miracle of short-circuit boolean evaluation). I
think the ‘correct’ answer to the typo-incorrect question is:

if a = (b or c or d or f)

To be super clear: this is only because we’re talking about assignment
instead of an actual equality test.

On 7/27/07, Ian W. [email protected] wrote:

Robert D. wrote:

You are right for sure that OP meant ==, but let us answer the
original question too

a = [b,c,d,e,f].compact.first

Not quite.

b=c=d=false
indeed well,spotted, same trap than in
x ||= 42