Association linking attempts to instantiate abstract class

[TimLethbridge]

The following Umple code generates invalid code that attempts to instantiate an abstract class. This problem only occurs due to the 1 end of the association. If the multiplicity is changed to 0..1, then the problem is not present.

class A {
  // The generated method A.addMyB() tries to instantiate the abstract class B.
  1 -- 0..* B myBs;
}

class B {  abstract; }

This problem was flagged by @gmussbacher gunter.mussbacher@mcgill.ca and is a high priority for his work. He might comment further.

Potential Solution 1: Detect associations which have multiplicity 1 at one end, and an abstract class at the other and and either:
a) Disallow such associations with an error
b) Raise a warning, and treat as a 1..* (similar to the way we handle directed associations
c) Simply avoid generating such a method in this exact case only

Option c is suggested.

[TimLethbridge]

PR #1187, it turns out, didn't fix all cases of this problem. Additional templates need to be adjusted in the same way. This should be straightforward. But we need to find all relevant templates this time.

The user reported the following case:

class A {
  // The generated method A.addMyB() tries to instantiate the abstract class B.
  // The problem has been fixed for multiplicity * but still occurs with any multiplicity greater than 1.
  1 -- 0..2 B myBs;
}

class B {
  abstract;
}