From: Gavin Sinclair <gsinclair@...>
Date: 2002-10-30T15:29:35+09:00
Subject: Re: "multiple assignment in conditional"


From: "Bulat Ziganshin" <bulatz@integ.ru>

>
> 1.7.3:
> GS>   a, b = foo and puts a
> syntax error
> GS>   (a, b = foo) and puts a
> works ok and prints 4

That's good news.  Thanks for the tip.


> 1.6.7 produces the same result as your 1.6.5. i think that problem is
> what "and" needs ONE value in first argument and your multiple
> assihnment supports TWO values :)

That's what I don't get.  It gets one value, not two:

  a, b = 1, 2                     # -> [1,2]

"and" should be able to deal with an array.

I'm surprised that
  a, b = foo and puts a
doesn't work in 1.7, because, as I said, "=" binds more tightly than "and", so
to my mind, that LOC should be exactly equivalent to
  (a, b = foo) and puts a

Can anyone explain why it isn't?


> btw, what you exactly want?
>
> a,b=foo; a and puts a
> or
> a,b=foo; b and puts a
> or
> a,b=foo; a and b and puts a
>
> ? ;)

I want
  a, b = foo and puts a
!

Since foo always returns non-nil, I want the equivalent of
  a, b = foo; puts a

It's really a matter of style.  The actual line of code is like this:

  results, duplicates = @scraper.get_backend_ids(last_record) and
    LOG.info "Retrieved backend IDs: #{results.length} of them"


Gavin