Re: Resolution of Dispatching Operations

[stt@houdini.camb.inmet.com (Tucker Taft)]

Matthew Heaney (mheaney@ni.net) wrote:
: I have a question about the rules for resolution of (dispatching) operations.

: I have a type with 2 operations that differ only with respect to whether
: the arguments are class-wide or specific:

: procedure Op (L : in T; R : in out T'Class);

: procedure Op (L : in T'Class; R : in out T);


: If I'm in a context where I have 2 class-wide objects and I call Op, which
: version of Op gets called?  Like this

: declare
:    O1, O2 : T'Class;
: begin
:    Op (O1, O2);
: end;

: On my compiler, the first version gets called, but I have no idea why that
: one would be favored over the other.

The compiler has a bug.  It should report the call (at compile-time)
as being ambiguous.

: My expectation is that at some point, either at compile-time or at
: run-time, I would get an error that says the compiler couldn't figure out
: which operation I meant.  What am I missing?

A bug-free compiler ;-).

: ...
: Matthew Heaney
: Software Development Consultant
: <mailto:matthew_heaney@acm.org>
: (818) 985-1271

-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA