Error when using the "param-record-as-scalar" method

[Felix Weinrank]

Hey all,

I'm recording parameter values using the "param-record-as-scalar" function and get an error with omnet 5.3p3:

<!> (omnetpp::cIntParImpl)RTXMethod: Cannot cast from type integer to double -- in module (inet::sctp::SCTP) sack.cli.sctp (id=123), during finalization

For example when recording the RTX method of SCTP:

**.sctp.RTXMethod = 4 
**.sctp.RTXMethod.param-record-as-scalar = true

This worked fine until Omnet 5.2

Greetings
Felix

[Michael Kirsche]

Probably the changes in the latest preview:
"Evaluation of NED expressions now uses integer arithmetic when operands are integers. Conversions that incur precision loss should now be explicit: converting a double to integer requires the int() cast; also, converting an int to double will raise an error if there is actual precision loss, and you can suppress that error by explicit double() cast. There are many smaller-scale changes related to this change -- see include/omnetpp/ChangeLog for details."

[Nikos Terzenidis]

This is a "bug" that I have also faced on a project that was migrated from Omnet++ 4.6

Probably only double parameters are allowed to be recorded in scalar files, but apart from that I cannot imagine how converting "4" to double incurs precision loss (and thus the error that results in not recording the param).

I think that it should be somehow "fixed" in future Omnet versions, since recording of simulation/module parameters is extremely useful during the interpretation of results. I don't believe that a simple cast from integer to double should prevent all integer parameters from being recorded in scalar files.

[Attila Török]

This whole "record-param-as-scalar" option was sort of a quick-and-dirty "solution" (by which I mean "ugly hack"). Given that parameters can not only be of int and double types, but strings, and others as well, they really should not be included as scalars, as those are always double. They should be a separate "result type", that can represent (almost) every parameter, no matter what its type is. We definitely plan to improve this in the future, as it is indeed essential for analysis.

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[Nikos Terzenidis]

Ok thanks for the feedback Attila!