Re: Type of Expression

Bernd Schoeller wrote:
> Hi,
> 
> is there a standard way to calculate the type of an ET_EXPRESSION
> within the gobo eiffel tools, assuming that I have already compiled
> the system?

There is no such thing as ET_EXPRESSION.type because the type of
the expression depends on the context. For example if we have:

class A
feature
    f is
        do
            print (foo.bar)
        end

    foo: X
end

class B
inherit
     A
        redefine
           foo
        end
feature
     foo: Y
end

class X
feature
     bar: ANY
end

class Y
inherit
     X
         redefine
             bar
         end
feature
     bar: STRING
end

The expression 'foo.bar' will have type ANY in the context of
class A, but type STRING in the context of class B. Perhaps
there is a way to have a function in ET_EXPRESSION which would
take a context as argument and would compute the type in that
context. I didn't do it though because it was deemed too
expensive for my needs. If you really need it I can dive into
that code again and see what I can do.

Another alternative is to run the dynamic type set builder
(used to detect CAT-calls) and then do something like that:

   a_feature.dynamic_type_set (my_expression).static_type.base_type

where `a_feature' is an ET_DYNAMIC_FEATURE (computed by the
dynamic type set builder) and `my_expression' is an ET_EXPRESSION
which appears in the corresponding feature. But in your case
running the dynamic type set builder might be even more expensive.

-- 
Eric Bezault
mailto:ericb-D6Qt/9opevxWk0Htik3J/[email protected]
http://www.gobosoft.com



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