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Re: [] Overload resolution and dynamic dispatch patch

Ok, understood. This conflicts with the way the current IA approach works. It is geared towards non-loaded resources and large, scalable repositories. The design assumes that it's impractical to load all relevant resources into memory, analyze and then memorize all dependencies for all OCL expressions for all context elements. Instead, it is analyzing the expression structure up-front, then deriving the change listeners which obviously need to be registered only on objects loaded into memory because only for those changes can be detected at all. Once a change occurs, the change is analyzed by traversing the element graph "backwards" using the expression structure. This also works for even the largest repositories because the memory required for backwards traversal doesn't grow with repository size.

It would be good if we knew which classes were generally available in the scope of a ResourceSet so as to scan their operations during backwards traversal ("traceback"). For the "traceback" approach this would consider all operations known/loaded at that time. The NavigationStep approach which is pre-computing the traceback paths would not work this way because it wouldn't know operations loaded through metamodels that become available after the IA has pre-computed the navigation steps.

What would be a good way to scan all existing operations and be notified when new subclasses with redefinitions / overrides become available? Wasn't there an open EMF bug requesting a notification mechanism for EPackage loads?

-- Axel

On 5/7/2012 9:06 PM, Ed Willink wrote:

a) unloaded Resources

In your earlier example with resource Y (unloaded) so that propagation
of 42 through resource X failed to impact:

Using my dependency analysis perspective, if the Y resource is not
loaded, I don't analyze it, I don't detect any dependencies, so I don't
install any listeners/notifiers to cause the Y resource elements to
react to changes. So I agree that it doesn't work. It's nothing to do
with EMF-based; it's just common sense.

not so common sense after all if a reference path leads through Y back
to X. Which resources from a repository an editor loads into a
ResourceSet is fairly random. JDT wouldn't be the same if errors in
Java resources not currently open in an editor remained undetected
until the resource is loaded.

Exactly. JDT knows how to open all files, and in order to report errors
it either loads everything or exploits some sort of memento of previous

It seems to be mandatory to load all resources for which any form of
analysis is to be performed. (It may be that they are unloaded retaining
only a memento, but they must be loaded to create the memento.)

Consider a doctor's patient list and the impact of a policy change to
invite all patients over 50 rather than over 60 to have a free flu
vaccination for the winter. The derived property of the number of
required injections can only be determined by examining each patients
records. If a patient's record is not loaded into the system/looked at
by a human, the accurate answer cannot be determined. It seems
unreasonable to expect to have impact or dependencies for unloaded

b) polymorphic calls

It seems that your traceback does not use the source object and so needs
to consider all possible operations. This seems inefficient and may lead
to fat notifications that can be filtered. The dependency perspective
knows the source object and so need only consider the relevant

I don't understand your "dependency perspective." Maybe you can
explain using the example I gave earlier?

For the derived property

context X::derivedProperty : Integer = self.m().i

on y1:Y, which is loaded so its dependencies are analyzed.
- it is a Y, so Y::m() which is self.b.a so depends on
-- the object identity at self.b, which is currently a B
-- the object value at self.b, which is b.a, so depends on
--- the object identity at self.b.a, which is currently an A
--- the object value at self.b.a which is i, so depends on
[---- the object identity i is not relevant since it is a data type]
---- the datatype value i

Each of the dependencies needs a direct or transitive notifier chain to
cause the change to propagate and in the case of identity changes, the
notifier chain to be adjusted.



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