Parse error: Modelica assignment statements

[Willi Braun]

Following model:

class test
  Real a(start = 1.0);
algorithm
  der(a) := a;
end A;

produce

Error: Parse error: Modelica assignment statements are either on the form 'component_reference := expression' or '( output_expression_list ) := function_call'

But it's legal Modelica.

[Adrian Pop]

This is not valid Modelica. Dymola supports it but the grammar does not allow it.
You can have function calls on the left hand side only in equation sections.
In the algorithm sections you can only have function calls on the right hand side.

[Willi Braun]

ah. ok thanks.

[Adrian Pop]

We can fix it fine, that's no issue, but i don't think we should.
I mean you could rewrite it to a := der(a); which is correct and
should work fine (i hope :) ).

[Willi Braun]

No, I don't think we should fix it. I just misinterpret der(a) as a variable name for $DERa, but it is more. At least it will make no sense when you consider something like this: der(a*b) := c this will expand to der(a)*b + der(b)*a and then it's an issue.