Hi,
jvlad schrieb:
Why would this create any problems? Say, you have class B that extends class
A and both do define one method and one property under the same names. Will
this create a problem? No. It's because there are rules that clearly
describe how it works (method and property will be overriden). Similar
approach may be applied to trait'ing classes. Why not? For example if you
have a property defined above trait'ing, it will be overriden by the trait
if it comes up with its own property with the same name (same goes for the
properties defined in the ancestor class). If trait defines a property, it
can be overriden by class if it introduce it below trait'ing statement.
On the other hand, if someone being a developer cares of potential
"conflict" (unwanted override), he/she may simply not define properties and
constants in the class that's intended to be trait'ed into another class.
This contradicts the idea behind traits.
Here all conflicts are handled explicitly. Overriding is not used
between traits to provide greater power and allow the notion of
flattening in the way it has been proposed.
Your proposal is much like mixins. But mixins have limited composition
power caused by this overriding. There are situations without a suitable
linearization to get overlapping methods from to different mixins in the
needed combination.
The complete argumentation can be found here:
http://www.iam.unibe.ch/~scg/Archive/Papers/Duca06bTOPLASTraits.pdf
illustrating the cons of mixins and multiple inheritance.
Kind Regards
Stefan
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