From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2008-08-30T11:20:05+09:00
Subject: Re: assignment operator that treats empty and nil as the same thing

On Aug 29, 6:01 pm, "scoot...@hotmail.com" <scoot...@hotmail.com>
wrote:
> ### test1
> otest   =   {};
> otest['first_name'] ||= 'homer';
> puts otest.inspect;
>
> ### test2
> otest   =   {'first_name'=>''};
> otest['first_name'] ||= 'homer';
> puts otest.inspect;
>
> Problem: test1 produces the correct output, but test2 produces
> unwanted output (the value remains as an empty string). I realize that
> ruby treats the empty string as "true" ... nevertheless I want to find
> an assignment operator in ruby that treats nil and empty exactly the
> same way, with the behavior shown in test1.
>
> Question: Is there a way to do this in ruby *without* resorting to an
> if statement or some other construct such as:
>
> otest['first_name'] = (otest['first_name'].empty?) 'homer' :
> otest['first_name'];
>
> I would like to handle this with a *single* assignment operator, just
> like you can do in test1.

The problem is that you think that otest['first_name] is nil in both
tests when you try the conditional assignment.  As the following code
shows it's only nil the first time;  the second time it's (an empty)
String.

otest   =   {};
puts otest['first_name'] .class.to_s
otest['first_name'] ||= 'homer';
puts otest.inspect;

### test2
otest   =   {'first_name'=>''};
puts otest['first_name'] .class.to_s
otest['first_name'] ||= 'homer';
puts otest.inspect;

HTH,
Richard