I've noticed that with addition of DoubleArrowedLine you've also added concept of "inverted" to attach points.

This seems really strange from the perspective that all methods

startingPointOf:

and

endingPointOf:

are identical only with swapped ifTrue:/ifFalse:

for example

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

this is harder to read and more error-prone than

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

plus there is code duplication. And this is just the simplest attach point.

Since I should also add "inverted" to my attach points that are in Roassal (RTRectangleAttachPoint, ...)

maybe the actual computation should be delegated?

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RTAttachPoint>>startingPointOf: anEdge

    ^ inverted

        ifTrue: [ self basicEndingPointOf: anEdge ]

        ifFalse: [ self basicStartingPointOf: anEdge ]

RTAttachPoint>>basicStartingPointOf: anEdge

    ^ self subclassResponsibility

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This also will not break current implementation but it will give opportunity to improve them.

And if there was a situation where the implementation would be actually different for inverted (and not just swapped values), than you could still just implement startingPointOf:/endingPointOf:

Thanks,

Peter