vahlberg@cs.uq.oz.au (Jon Vahlberg) (06/01/91)
Hello,
I've got a slight problem with an eiffel program
and I am not to sure how to solve it. I would appreciate
it if someone could tell me a solution.
The problem in hand
is that, I want a generic class (let's call it XSet) which
takes any type. It is basically a set of elements. Now, I want
an operation called In, which given an element, tests to see whether
the element is in the set. Sounds easy enough so far. Now the
problem is these elements may have attributes which are strings
and I would like to test each the members of the set based on the contents
of these attributes, not on their references, for the element.
I have written and
can assume for all members being passed that they have the
function Equal defined for them. Either it has been explicitly
defined or just inherited from Any. Those types which have
strings for attributes, have Equal defined in them, that does
the testing on the contents of the string (whereas Equal in ANY
just checks the reference value). The major problem is that
in the operation In, where I use the operation Equal to test,
it uses the operation Equal from Any and not from the one defined
for the element. Is there a nice, clean way around it?
If this problem is stated too ambiguously, send me a email
and I'll discuss it further.
Jon.