From: Robert Klemme <shortcutter@...>
Date: 2009-01-05T06:44:00+09:00
Subject: Re: Finding filename from a URL

On 04.01.2009 21:46, Rob Biedenharn wrote:
> On Jan 4, 2009, at 1:04 PM, Robert Klemme wrote:
> 
>> On 04.01.2009 17:29, Sam Fent wrote:
>>> This is just a basic parsing question, really. I'm trying to work out
>>> how I would process a URL such as
>>> "http://www.example.com/x/y/z/myfile.txt" and get back the filename
>>> "myfile". Basically the pattern is to get the past part of the string
>>> after the final /, and then strip off the filetype.
>> IMHO it is not a good idea to use a File method for URL's because  
>> File.basename has different criteria
>>
>> irb(main):003:0> File.basename 'http://test.com/aaa\\bbb.txt'
>> => "bbb.txt"
>>
>> Although I am not sure whether a backslash is allowed there, this is  
>> what I'd do:
>>
>> irb(main):001:0> url = 'http://www.example.com/x/y/z/myfile.txt'
>> => "http://www.example.com/x/y/z/myfile.txt"
>> irb(main):002:0> name = url[%r{[^/]+\z}]
>> => "myfile.txt"
> 
> Rather than jump to a Regexp, just use the right tool for the job.
> 
> irb> require 'uri'
> => true
> irb> u=URI.parse 'http://www.example.com/x/y/z/myfile.txt'
> => #<URI::HTTP:0x1cac14 URL:http://www.example.com/x/y/z/myfile.txt>
> irb> u.path
> => "/x/y/z/myfile.txt"
> irb> File.basename u.path, '.txt'
> => "myfile"

I considered URI as well but what makes your code the "right tool for 
the job"?  Basically you use URI only to extract the path and then use 
File.basename to get the last bit of the path.  But: while the URI path 
consists of elements separated by "/", File.basename also considers "\\" 
as delimiter.  So IMHO it is by no means "the right tool" - at least not 
more than using a regular expression which extracts exactly the part 
needed from the string at hand (and is likely faster as well).

The situation would be different if URI provided a method which returns 
the last path element but as far as I can see this does not exist.

Kind regards

	robert