Array of tasks and using its index as discriminant

[JC001]

@DrPi

Why a default for the discriminant is needed ?

Without a default discriminant, the type is indefinite; you can’t declare an object of the type without providing a value for the discriminant:

task type Do_Segmented_Block_Type (Tactic : Segmentation_Tactic);

V : Do_Segmented_Block_Type; -- Illegal

Array components have to be definite. Adding a default discriminant makes the type definite:

task type Do_Segmented_Block_Type (Tactic : Segmentation_Tactic := Segmented_1);

V : Do_Segmented_Block_Type; -- OK, discriminant is Segmented_1

@charlie5

To make it mutable ?

Tasks cannot be mutable.

@jere

As mentioned above, compilers like GNAT pick the largest size variant and allocate that amount always (which can be wasteful if one variant is really big and all the others are smaller). Other compilers like JanusAda will instead just use a pointer in the record and heap allocate under the hood.

I don’t see any mention of this “above” in this topic. Am I missing something? There is a reference to this in this topic. While relevant to variant records, it’s not an issue for task types.