From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: What good are File_Access's?
Date: 1998/07/18
Date: 1998-07-18T00:00:00+00:00 [thread overview]
Message-ID: <dewar.900786542@merv> (raw)
In-Reply-To: 6oo80p$m20$1@nnrp1.dejanews.com
T.E.D. said
>It looks to me like the whole point of the File_Access type in Ada.Text_IO is
>to allow Standard_Output and Current_Output (and the same functions for Input
>and Error) to be compared in order to see if I/O has been redirected somehow.
>However, when I compile and execute a DOS program using ObjectAda on NT,
>Ada.Text_IO.Current_Output and Ada.Text_IO.Standard_Output are *not* equal. If
>I do an Ada.Text_IO to either, it gets printed in my shell window.
>
>So if I can't use the equality operations of File_Access to see where output
>is going, what was the type put in there for? There's nothing else other than
>the Standard* and Current* functions that give me one, and the only
>operations allowed are equality comparison and assignment.
No, the point of this feature is to allow you to save and restore the
value of Current_Output. Ted's theory is interesting, but there is nothing
in the RM to suggest that this equality test is expected to work, let alone
required to work!
Indeed it is easy to imagine that two values designating the same file
would very likely not be equal.
next prev parent reply other threads:[~1998-07-18 0:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-07-17 0:00 What good are File_Access's? dennison
1998-07-17 0:00 ` Tucker Taft
1998-07-18 0:00 ` Robert Dewar [this message]
1998-07-20 0:00 ` dennison
1998-07-20 0:00 ` Robert Dewar
1998-07-20 0:00 ` dennison
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