Variables (computed messages)

[emil14]

Package wide variables i.e. computed values (at runtime or compile time) and not just consts

• Compile time executed
• Runtime executed

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Related to #87 #242

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Do we need runtime functions for that?

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From "dataflow programming" book:

Instead of
storing state internally in the node, it would send its state data on
the output so that in the next activation it can read it back in.

[emil14]

Loop based pattern

in.sig -> computation.sig

computation.result
  -> out.result
  -> computation.sig

So user of this component can use it just like an IIP, it just have to trigger it once and the whole thing will never stop sending the result message

Problems

1. How to implement this for variables that depends on data (think for errors.New("..."))
2. Can we introduce some abstraction to simplify this pattern to make user not code it by him/herself?

[emil14]

Re-open when (if) needed