On 28 juil. 2011, at 23:10, Nicolas Anquetil wrote:
I want to reimplement software engineering metrics using moose chef instead of moose cook.
for example to compute cohesion I would do (among other things):
self queryAllOutgoingDependencies atClassScope withinMyPackage
i.e. :
1- from a package (self)
2- get all its "outgoingdependencies" (outgoing does not mean going outside the package, this includes dependencies within th package)
3- put that at class level (because we are interested in dependencies between classes within or outside the package)
4- and filter those that are inside self
OK, I see what you mean. When I refactored Cook into MooseChef, there was lots of small decisions about the "best" default choice i.e., the least surprising choice. Unfortunately I also realized that such choices do not work in all cases. The underlying principle is that default choices in MooseChef works best bottom-up: that is, starting from the low-level entities (methods, classes) up to enclosing entities (classes, packages). Conversely, you have to be careful when working top-down and that's because of the self loops exclusion.
So my proposed solution for this is to work "bottom-up": instead of collecting dependencies directly at package level, you start to work at class level.
aPackage classes collect: [ :class | class queryAllOutgoingDependencies atClassScope withinMyPackage ]
But again, this might or might not be the expected result because you exclude self loops at class scope then (i.e. no ClassA -> ClassA relation, this might or might not be what you want). If this is not what you want, you might go to the level of methods, and then again self loops are exclude but at method level (i.e. recursive calls are excluded).
I really don't know what's the best:
- keep the current semantic which plays nicely bottom-up (however, the above case shows it's not really consistent with "least surprise" :) )
- or be less intelligent and let the user chooses himself whether or not he wants self loops as proposed by Doru. This way MooseChef would be more adaptable to any case.
I am not very happy with the proposed API enhancements but it can be a temporary solution. I would rather make #withoutSelfLoops works with MooseObjectQueryResult (currently, #withoutSelfLoops works only with primitive queries). Then I could write (for example):
aPackage queryAllOutgoingDependencies atClassScope withoutSelfLoops
I want the result to be all dependencies from classes within package self going to classes within package self.
but (from the moose chef documentation):
"The scope operators exclude self loops by default (this was also the default in Moose Cook). That is, the query result will not contain the receiver scope itself: you will not get something like PackageX -> PackageX in the result (the reason for this is that in general algorithms do not like graphs with self loops)."
So:
- should we change that default?
- should I change my query?
I believe if there is a method to exclude self loops (withoutSelfLoop), it should not be done automatically in some case let those who want it do it themselves.
What say you?
nicolas
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