From: Lionel Bouton <lionel-subscription@...>
Date: 2007-09-05T07:08:25+09:00
Subject: Re: Why does File.exists? not support regexp? It would be very handfull?

Joel VanderWerf wrote the following on 04.09.2007 23:47 :
> Gary Wright wrote:
>>
>> On Sep 4, 2007, at 12:00 PM, kazaam wrote:
>>> On Wed, 5 Sep 2007 00:52:57 +0900
>>> Daniel Berger <djberg96@gmail.com> wrote:
>>>
>>>> Dir["fglrx*"].each{ |file| File.delete(file) }
>>>>
>>> that's pretty much the same like: system('rm -f fglrx*') but I'm
>>> asking why one doesn't allow regexpr into File.exists?
>>
>> I would guess it is because file name pattern matching
>> is subtly different from string pattern matching.  In
>> particular you have the problem of directory hierarchies
>> and how to handle the separator character (typically '/').
>> The common file pattern syntax is also *not* the same
>> as general regular expressions.
>
> The slocate(1) program does have a -r option for searching file paths
> with a regex, so there is some precedent.
>
slocate uses it's own database, not direct file access. File.exists?
uses a system call directly. Using regexes would need to list all files
that could match (a directory or the whole virtual filesystem depending
on what you are matching with: a filename in a given directory or a
path). This is far from a common need and in the general case far too
slow: developpers are better off coding the regex matching code
themselves and optimize it by listing the smallest subset of filepaths
the OS can give them before they filter with a regex (which is trivial
to do in Ruby anyway)...

Lionel