RE: Another V5R1 query... Qualified DSs

[Jon.Paris@xxxxxx]

 >> It may be just me, but this is why I wanted to have the same field
names in data structures.

But what you are asking for is impossible Brad.  Well - it is a computer so
I guess nothing is impossible but .... at the very least highly
undesirable.

A DS is a discrete piece of memory.  The fields within it merely map that
piece of memory to different formats.  So you can not have the same field
in two different DS because each represents a different chunk of memory.
RPG gives the appearance of allowing this to happen (i.e. you can have the
same field name in multiple files) but under the hood the compiler
generates code to move the data from/to the I/O buffer and into the
discrete field storage.

The compiler could recognize that if a field name was duplicated that every
move into it should also go to the other versions in other DSs but (and it
is a very big but) what do you expect to happen when I move data to the DS
at the DS level?  Should the compiler recognize that the underlying field
has changed and copy that field to the other DS (yuck!).  Same applies if
the field is overlaid in any way.  What about when I/O takes place?  Which
of the various copies of the field do I take the data from on output?  It
just gets too nasty for words.

The best option IMHO is the one mentioned earlier by Gary - which is that
Hans and Barbara will give us an equivalent to COBOL's MOVE CORRESPONDING.
That deals with the issue of having to move field by field.


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