From: Jeremy Tregunna <jtregunna@...>
Date: 2005-09-22T17:25:21+09:00
Subject: Re: Argument passing with |boofar| (fwd)


On 22-Sep-05, at 4:15 AM, Jurgen Stroo wrote:

> Lo Fellow listers,
>
> I already mentioned I am starting to learn Ruby the last couple of 
> days.
> I came across the following in the Prog. Ruby book:
>
> File.open("songdata") do |song_file|
>   songs = SongList.new
>   song_file.each do |line|
>       file, length, name, title = line.chomp.split(/\s*|\s*/)
>     songs.append(Song.new(title,name,length))
>   end
>   puts songs[1]
> end
>
> I previously read about the argument passing between methods and code
> blocks. They used explanations of this construct which were indeed 
> clear
> to me:
>
> ('a'..'e').each {|char| print char}
>
> this each method is of course iterating over the list and returning the
> value each time for each list entry, which is passed as the variable
> 'char' in the block. (correct me if I'm wrong)

It's iterating over the range, not the list; but that's a minor point.

> But, in the case of:
>
>   File.open("songdata") do |song_file|
>
> what is returned then? I mean, the File.open is just a statement 
> without a
> return value, or isn't it?

It's yielding the file object itself, which you can work with, and will 
be automatically closed when the block finishes.

> Jurgen

--
Jeremy Tregunna
jtregunna@blurgle.ca

"If debugging is the process of removing bugs, then programming must be 
the process of putting them in." --Dykstra