Re: AI-248 and counting the elements in an external file

["Randy Brukardt" <randy@rrsoftware.com>]

Larry Kilgallen wrote in message ...
>In article <3ECFEB59.4010401@attbi.com>, "Robert I. Eachus"
<rieachus@attbi.com> writes:
>> Larry Kilgallen wrote:
>>
>>> Meaning it is permissible to return the number of 512-byte disk
blocks
>>> (or file-specific-size tape blocks) for this function on VMS ?  Or
is the
>>> answer supposed to be normalized to bytes even though the number of
>>> overhead bytes required (and thus the file size) will vary, for
instance,
>>> when copying a file from disk to tape ?
>>
>> Let me answer differently.  VMS supports many file formats.  Ada
stream
>> files would map nicely to VMS record oriented ANSI tape files.  There
>> are other VMS formats that I would not tend to support stream files
for.
>
>But my understanding is that the Ada.Directory functions are to support
>all files that might be accessed from Ada, and that is not limited to
>stream files, nor to files written by Ada.

The intent is that it be well-defined (which might include raising
Use_Error if if cannot be figured out, as for a keyboard) for files that
can be read or written by Ada. If Ada doesn't understand the files at
all, then we're not trying to say anything.

I would expect that this functionality would take more work on some OSes
than it does on Windows or Unix. On the original CP/M, for instance, you
had to figure out the file size by finding out the block size and
multiplying it by the number of blocks. That's fine, and keep in mind
that this result really is intended to report the physical size of the
file, which may or may not be directly relatable to the 'logical' size
returned by Direct_IO.Size and Stream_IO.Size.

             Randy.