Re: Size and pack

["Jeff Creem" <jeff@thecreems.com>]

OK.. I know I am going to regret this since whenever I question Robert I
usually am wrong however
without using the complete context of this thread, I believe Roberts
statement is actually
a little too broad. There ARE indeed times when you want a pragma pack and a
rep spec. Not for the record case but for arrays of items that have been rep
spec'ed.

for example, the code fragment

type My_Type is range 0 .. 3;
for My_Type'size use 2;

type My_Array is array (1 .. 4) of My_Type;
pragma Pack (My_Array); -- Without this the following could fail
for My_Array'size use 8;


The pragma pack is needed I believe because the rep spec on My_Array can
be rejected without it (At least it has been rejected by some compilers and
I forget
the exact rule but it had something to do with the final rep spec not being
allowed to
change the layout of the items within the array).

Having said that VADS used to compile this without the pragma pack. Green
Hills did not.
I *THINK* GNAT does allow it to go through without the rep spec for several
versions now.


"Robert Dewar" <dewar@gnat.com> wrote in message
news:5ee5b646.0110301750.38ba5bfd@posting.google.com...
> john.mccabe@emrad.com.nospam (John McCabe) wrote in message
news:<3bc41989.4285341@news.demon.co.uk>...
> > Your best bet would be to use as many representation attributes as are
> > necessary. In general I would use both a representation clause and
> > pragma pack
>
> No, that's pointless, if you use a complete rep clause, then it is
> redundant to use pragma Pack since it won't have
> any effect.