Enable the usage of a pre-built model executable when instantiating ModelicaSystem

[joewa]

Related Issues

This pull request was inspired from the discussion in issue #151

Purpose

• Enable the usage of a pre-built model executable when instantiating ModelicaSystem. This will gain some efficiency e.g. when only the parameters or the input data changes between different simulation runs.
• Apply the customization (variableFilter or overrides in general) when calling the pre-built model executable (as an alternative to the variableFilter that can be passed to ModelicaSystem or buildModel that was introduced in issue ModelicaSystem.simulate() does not handle 'outputFormat' and 'variableFilter' options correctly. #151).

Approach

ModelicaSystem will not to call buildModel when the xmlFileName of the pre-built model is provided.

from OMPython import ModelicaSystem
mod = ModelicaSystem(
      fileName=`BouncingBall.mo`, modelName='BouncingBall',
      xmlFileName='BouncingBall_init.xml'
  )

The simulation can be executed with a customized set of output variables and stopTime like this:

res_vars = ['h', 'v']
log_str = str(mod.simulate(
    resultfile='/tmp/bouncingball_res.mat',
    simflags=None,
    overrideaux='stopTime={0},'.format(stopTime) + 'variableFilter="'+'|'.join(res_vars)+'"'
))

The log_str contains the models output from stdout and stderr.

Thanks to @Nobby-n and @arun3688 for contribution and inspiration.

[CLAassistant]

All committers have signed the CLA.

[joewa]

I am happy to provide this PR @arun3688

[adeas31]

@joewa please rebase this to the latest code.

[syntron]

perhaps wait a moment - currently lots of changes are ongoing ;-)

[joewa]

Please let me know when you think that the time is right @adeas31 @syntron
Then I will rebase.

[syntron]

@joewa please check PR #275 - I will prepare the code in it as single PRs; however, you could check out what to expect:

Class ModelicaSystemCmd would handle the execution of commands / calling the model executable. That way, the options (simflags / new: simargs) can be handled dynamically. Thus, any option could be overwritten (override!) as needed. See especially commit 2bd6754 which was created for this usecase.

[syntron]

@joewa feel free to work based on PR #279