Couldn't we solve this with a featuremap? I only read about
featuremaps and never actually used one. But as far as I understand,
we could create a transient/volatile reference that aggregates two
references and allows any ordering of the resulting mixed
collection. Such a map could merge Units and ParameterMappings and
would allow to define the order in which they should be executed.
E.g.:
+ AnyUnit u
+-- Param X
|
+ SequentialUnit su
+-- Param Y
+-- Param Z
+-- PM Y -> X
+-- AnyUnit u
+-- PM Z -> X
+-- AnyUnit u
This would require that the execution of su would accumulate
parameter-values as defined by the mappings until it reaches a
subUnit which is then executed. After the execution the unit will
continue accumulating mappings until it reaches the next subUnit,
etc.
Using a common interface UnitStatement for ParameterMappings and
TransformationUnits seem problematic because of the containment of
ParameterMappings.
Perhaps we should clarify whether we are just looking for a quickfix
here or if this would be a good occasion for a critical
reexamination of the controlflow in general.
Regards,
Gregor
Am 14.01.2012 10:44, schrieb Enrico Biermann:
I am not sure I see the problem. The parameter relation mapping
between a unit and one of its subunits should be injective. The
parameter relation mapping between a subunit and its unit (also
stored in the unit) should be injective. Any non-injective
relation will always have the problem of having to choose which
value to apply to a subunit (or the unit). Even if A->X,
B->X wouldn't be ambigous in the first place. Trying to put
them in a proper order like A->X first, then B->X second is
futile at the moment.
Note that the injectivity apply only between the unit and exactly
one subunit. You can reuse unit parameters for different subunits
as well as set unit parameters with parameters from different
subunits.
One possiblity would be
A -> X
B -> Y
And allow a syntax to map multiple parameters to a single field
for example:
attribute = {X|Y}
Another would be to use guards for parameter mappings i.e. allow a
specific mapping only if the condition is true. However I have no
idea what kind of information you would need here. Probably things
like state of parameters and information about previously executed
subunits.
I am not happy with either of these solutions and not sure whether
the injectivity restriction is that bad.
Regards,
Enrico
On 13.01.2012 23:20, Christian Krause wrote:
Assume you have a sequential unit with parameters A and B in
which another unit with a single parameter X is called twice.
The first time, it should be invoked with A, the second time
with B. So I have to add the following parameter mappings to the
sequential unit:
A -> X
B -> X
But now, when the subunits are invoked, the engine should get
into trouble because it does not know whether to pass A or B for
X.
On 01/12/2012 12:53 PM, Stefan Jurack wrote:
Right, analogously to method calls where the caller passes parameters to
and fetches parameters from the callee.
Am 12.01.2012 12:26, schrieb Christian Krause:
Hi,
parameter mappings are managed by the parent transformation unit,
correct?
chhers,
christian
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