Re: What good are File_Access's?

[dennison@telepath.com]

In article <dewar.900954709@merv>,
  dewar@merv.cs.nyu.edu (Robert Dewar) wrote:
> <<Ahhhh. That's the answer I was looking for.
> I didn't consider that as a possibility because that method of saving off the
> Current_Output won't work in a multi-tasking environment. You'd need some kind
> of "atomic" save-and-change operation. Since that is %90 of the Ada programs I
> have ever worked on, that doesn't make it too useful.
> >>
>
> Well it simply needs protecting in a multi-tasking environment. You generalloy
> need to have some control over Text_IO anyway (for example, you certainly
> cannot do Put_Line operations on standard output at the same time from
> two separate tasks without proper synchronization.

True. But having to manage task access to the same *file* is a little
different than having to manage task access to the global default for all of
Text_IO. The former can be accomplished by the simple rule "only task X gets
to access file Y" (or by more complicated means). The latter ... hmmm ... it
would be grisly.

You'd really need a default for each task. I guess you could reimplement all
of Text_IO as a task, using Caller ID's to index into an array of defaults.
Yuk.

Yeah, its basicly useless.

T.E.D.

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