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From: Kilgallen@SpamCop.net (Larry Kilgallen)
Newsgroups: comp.lang.ada
Subject: Re: File manipulations in Ada.Text_IO
Date: 2 Aug 2005 07:31:02 -0500
Organization: LJK Software
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In article <suydneKD44DoEnPfRVn-ug@megapath.net>, "Randy Brukardt" <randy@rrsoftware.com> writes:
> "Larry Kilgallen" <Kilgallen@SpamCop.net> wrote in message
> news:67kFmodka+Zb@eisner.encompasserve.org...
>> In article <wauHe.7071$0C.1043@newsread3.news.pas.earthlink.net>, Jeffrey
> Carter <spam@spam.com> writes:
>> > Georg Bauhaus wrote:
>> >>
>> >> One way using standard Ada is an attempt to open the file.
>> >> If the external file doesn't exist, exception Name_Error
>> >> is raised.
>> >
>> > Ada 0X will have Ada.Directories as part of the standard library, which
>> > will include such a function.
>>
>> But such a function for a non-wildcarded filename is always going
>> to be susceptible to a race condition if the next step would be
>> to open the file.  The file might be deleted or created between
>> the test and using the information gained from the test.
> 
> True, but that's a general problem with I/O, not specifically with the
> directories operations. Generally, if you're doing I/O, you have to handle
> exceptions and never assume that they won't be raised, no matter what
> pretests you might have done.

Yes.  My point is that the utility of checking first before attempting
to open a file is vastly overrated.