prototyping of parameter descriptor

[Ichthyostega]

As a Lumiera developer,
I need at least a preliminary placeholder definition,
to be used as parameter representation at various interfaces

immediate goals

• drive the analysis ahead to identify the fundamental structures at work
• settle on an implementation approach and derive a solid guess regarding required data size
• provide the ability to store a simple data value as parameter
• have extension points to control the domain and scale

[Ichthyostega <prg@…>]

In 3764479/Lumiera:

Parameters: detailed the prototype design sketch (see #1431)

Last week, I resumed the work that had been suspended
due to my focus on this year’s Froscon talk (on io_uring).
I have reconsidered my previous design ideas and sought to
arrive at a coherent design. Nevertheless, these are preliminary,
exploratory design studies that should be regarded as a basis
for future work rather....

[Ichthyostega <prg@…>]

In f224441/Lumiera:

Parameter: simple testcase PASS (see #1431)

Add value access implementation of the Provision interface
by direct cast and access to the embedded value in ParamData<VAL>;
obviously this is an indirect dispatch, based on the actual type VAL

The test demonstrates the basic machinery built thus far

• have an embedded container with inline storage
• dispatch using type information encoded into the VTable