From: "David A. Black" <dblack@...>
Date: 2008-03-15T22:31:01+09:00
Subject: Re: baffling undefined method error

Hi --

On Sat, 15 Mar 2008, Tom Cloyd wrote:

> I'm getting an error I can't account for. In a method I've written I open a 
> file and access a yaml store:
>
> archive_stored_list = 'archive_stored_list.yml'
> archives_stored_catalog = File.open(archive_stored_list) {|i| YAML.load(i)}
>
> I massage the data a bit, and want to write it back out to the same file. I 
> try to close the file so I can open it for output, but get an error:
>
> archives_stored_catalog.close # <= "undefined method `close'" error is 
> written to log file here
> open(archive_stored_list,"w")  {|i| YAML.dump(archives_stored_catalog,i)}
>
> Why is this giving an error? Isn't the IO.close method always available? Very 
> confusing.
>
> This usage is straight out of Programming Ruby 2nd edition, but it doesn't 
> work for me, and I can't see the error.

When you use a block with File.open, the filehandle is closed
automatically when the block exits. There's no point even saving it,
because the value of the whole operation will be nil.


David

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