From: Tim Greer <tim@...>
Date: 2009-01-10T08:29:38+09:00
Subject: Re: value of an expression?

Kedar Mhaswade wrote:

> 
>> It is the equivalent of:
>> 
>> if (1 + 1 != 2)
>>      s = "surprising"
>> end
>> 
>> So s = "surprising" is never evaluated, and s continues to equal
>> "test".
> 
> Ah ok, thanks. However, I was thinking if it should be nil, not
> "surprising", because of the following experience with irb:
> 
>>> "surprising" if (1+1 !=2)
> => nil
> 
> which gives an impression that the value of this entire expression is
> nil.
> 
> -Kedar
> 

That's because the conditional isn't true.  If the conditional wasn't
nil, it would have a result (no result is nil):

irb(main):008:0> s = "surprising" if (1+1 != 2)
=> nil
irb(main):009:0> s = "surprising" if (1+1 == 2)
=> "surprising"
irb(main):010:0>   

See, for example:

irb(main):010:0> s = 'value'
=> "value"

See that "puts s" has no result, you see => nil.
irb(main):011:0> puts s
value
=> nil

It does what it is supposed to do:
irb(main):010:0> s = 'value'
=> "value"
irb(main):011:0> puts s
value
=> nil
irb(main):013:0> s = "surprising" if (1+1 != 2)
=> nil <- conditional false, nil.
irb(main):014:0> puts s
value
=> nil
irb(main):015:0> s = "surprising" if (1+1 == 2)
=> "surprising"  <- conditional true, not nil.
irb(main):016:0> puts s
surprising
=> nil

These results don't change what 's' is assigned, unless it's true and s
is assigned a different value.

I hope that makes sense.
-- 
Tim Greer, CEO/Founder/CTO, BurlyHost.com, Inc.
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