Prof. Dr. Johannes Grabmeier wrote"
>
> I observed the following behaviour. Perhaps someone can tell what is
> going on, a bug of philosophy which I do not understad? If necessary I
> can work out and provide a minimal example.
>
> 1. defined a category IML with several functions, all of them are
> implemented in the category, some of them use local pointer variables of
> the form
> pF1: Reference Boolean :=3D ref false
> in the add-part of the category
>
> 2. implemented domains (eg. DatabaseTable) which use this category via
> Join(IML, ...) with ..
> it works like designed: I can set from outside new values to the
> Reference values, and then on the Boolean values depending functions of
> the domain the set values
> (from outside) are used and change the behaviour of the functions.
> (mainly: information on intermediate values of variables)
>
> 3. implemented a package which use this category via IML with ...
> Different behaviour: alll function codes from IML are available as
> signatures of the package, there compiled code from IML- is available
> and can be executed. The internal
> variables - as in 2. - can be set from outside, the functions which
> return the actual values show the changed values. HOWEVER, the code of
> other functions in the package
> do not realize, that the derefenced values are changed -- CONTRARY
> to the identical settings in the domain case of 2. Then, the attempt to
> repeat the definitions as
> pF1: Reference Boolean :=3D ref false
> in the add-part of the package does NOT CHANGE this behaviour.
> However, in this package a domain(DatabaseTable) which also has the categor=
> y
> IML implemented, is imported. Executed code now uses THE internal
> values of pF1 of this domain for the execution of a function from the
> package. Can it be, that the compiler
> is confused and uses the wrong variable? This suspicion is confirmed
> when I finally did a package call to % explicitly.
Hmm, I do not know what you expect. First, the add part of category
is a special package. For each domain/package of the category you
get a separate copy of this package (normally you get a single copy
for each tuple of parameters, but add part of category has the
domain as a parameter).
Second, variables in different domains/packages are completely
separate. In particular your domain/package does not directly
see variables from IML -- the whole effect of variables in
add part of IML is that they are visible to functions in
add part of IML.
Your problem may be that the compiler calls different
function than the ones you expect: in case when multiple
functions share signature the compiler will just choose
one of them.
BTW: I do not understand why you use references. Normally
references are used when you want to modify values from
places were variables are not visible. That frequently
means hairy logic and I would first search for errors
in such logic.
--
Waldek Hebisch
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