From: "David A. Black" <dblack@...>
Date: 2008-03-15T23:01:01+09:00
Subject: Re: baffling undefined method error

Hi --

On Sat, 15 Mar 2008, Dave Thomas wrote:

>
> On Mar 15, 2008, at 8:24 AM, 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.
>
>
> The block form of IO.open returns the value of the block. So, what is the 
> class of archives_stored_catalog? It isn't an IO object. It's your loaded 
> YAML data. So it doesn't have a close method.

Yeah, that :-) (I said nil, which was an over-generalization from a
case where the block called puts.)


David

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