From: Dark Ambient <sambient@...>
Date: 2006-07-08T05:19:57+09:00
Subject: Re: Question : Pickaxe example

Thank you , that helps!  The part that was throwing me was the 'Ruby
Tuesday' myarray[0], I'm gathering since it's the first to come before
the puts statement it shows.

Stuart

On 7/7/06, Matthew Smillie <M.B.Smillie@sms.ed.ac.uk> wrote:
> On Jul 7, 2006, at 12:28, Dark Ambient wrote:
>
> > I'm reading through part 1, blocks and iterators section.  Lots to
> > digest here :)
> > Anyway, there is discussion about implementing a search for songs,
> > called 'with_title'
> > Even though the first code example is not the one that ultimately gets
> > used I think for me it's important to understand it, so I tried
> > recreating it outside the actual application. I'm getting some errors
> > and would appreciate some feedback.
> >
> > Here is the code (I've used some puts statements to see what's
> > going on)
> >
> > def with_title (title)
> > myarray = ['Ruby Tuesday', 'Paint it Black', 'Lets Spend the Night
> > Together',
> >                'Mothers Little  Helper', 'Jumpin Jack Flash']
> >                         for i in 0...myarray.length
> >
> >                            puts myarray.length # added in to debug
> >                            puts 'here is i: ' + i.to_s # added in
> > to debug
> >
> >                return myarray[i] if title == myarray[i].title
> > #leaving .title in causes an error
> >
> >     #about undefined method
>
> What it does is call the #title method on myarray[i], but in your
> example, myarray[i] is a String, which doesn't have a #title method -
> hence, undefined method.  I believe (my copy is at the office) that
> the example in the book uses a Song class which has the title method
> defined.
>
> >                puts 'here is myarray[i] ' + myarray[i]
> >              end
> >            end
> >
> >            with_title('Paint it Black')
> >
> > If in this line
> > return myarray[i] if title == myarray[i].title <------ I removed the
> > .title from the right side of
> >
> > the equality statement, myarray[i]
> >
> > I get this back:
> >
> > 5
> > here is i: 0
> > here is myarray[i] Ruby Tuesday
> > 5
> > here is i: 1
>
> Which is exactly what I'd expect.  myarray[1] is 'Paint it Black'.
> The next statement after printing 'here is i: 1' is to return the
> current title if it matches the title being searched for.  They
> match, so the method returns.
>
> The usual idiom in Ruby omits explicit return statements, and relies
> on the language to return the value of the final expression evaluated
> in the method.  An explicit return statement exits the method,
> returning the specified value immediately.  In this case, it's used
> as a way to stop the loop once a match is found, presumably with the
> assumption that either you only need the first match, or that only
> one will exist.
>
> matthew smillie.
>
>
>
>