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taurus-org / taurus

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(doc) Improve v3->v4 migration guide #1057

Closed cpascual closed 4 years ago

cpascual commented 4 years ago

The Migration guide suggests using TangoDevice.stateObj.read().rvalue as a replacement for the deprecated TangoDevice.getState(), but the behaviour is not identical since the suggested replacement uses cache. Change docs to suggest a closer replacement.

reszelaz commented 4 years ago

Thanks for the PR!

@cmft points that the TangoDevice.getState in taurus 3 was also returning the value from the cache by default. So, to be 100 % equivalent we should do the same with TangoDevice.stateObj.read().rvalue.

However there is another case: TaurusDevice.state() which in taurus 3 used to work and was actully reading the "State" attribute via PyTango, now does not work. The migration guide should either propose: TaurusDevice.read_attribute("State").value or eventually TangoDevice.stateObj.read(cache=False).rvalue. The first option will still use PyTango, the second option will use taurus but with the same result as when used with taurus 3.

cpascual commented 4 years ago

Thanks @cmft and @reszelaz for pointing this out. I am closing this ticket as rejected and opening #1059 wich also fixes a related issue.