Re: Mixing reading and writing to a text file

[msimonides@power.com.pl]

On 3 Sie, 03:26, "Randy Brukardt" <ra...@rrsoftware.com> wrote:
> <msimoni...@power.com.pl> wrote in message
[...]
> > The problem I have is with writing the state information back to file.
> > Ada.Text_IO and Ada.Streams.Stream_IO only allow opening file for
> > input or for output. In the latter case the file is being truncated
> > (as far as I understand the ARM).
>
> The ARM was screwed up in Ada 95 vis-a-vis Ada.Streams.Stream_IO. This was
> fixed in the Amendment (and the fix is supposed to apply to Ada 95 compilers
> as well). Specifically, stream files are *not* truncated when they are
> opened for output (otherwise it would be virtually impossible to use the
> positioning functions to write a stream file).
>
> But a warning: almost all compilers got this wrong when we tested them while
> we were working on the Amendment.
[...]

Thanks for clarification. I wrote a simple test that opens an In_File
and then Resets it as Out_File and writing works as expected - data is
overwritten over the bytes that I wish to change and there is no
truncation (the compiler is GNAT GPL 2007).

(I have read A.8.2 File Management and only skimmed over description
of Ada.Streams.Stream_IO, so this has been mostly an RTFM issue :) ).
--
Marcin Simonides