Add new VType class in Phoebus to manage Description in Enum and manage Labels properly in PVTable

[katysaintin]

Hello @shroffk and @kasemir ,

Here is my proposal for fix Description and Enum values in waiting epics-base/epicsCoreJava#141
resolution. Perhaps it will help you to fix it in epics core-vtype module .

• Add a new interfaces and classes in phoebus core-vtype :

1. DescriptionProvider to manage description on VBoolean and VEnum (normally VType should implement it) .
2. EnumProvider to manage ONAM and ZNAM for Boolean value and get EnumDisplay for example "ON, OFF" ..
3. AdvancedBoolean that implements DescriptionProvider & EnumProvider and extends VBoolean
4. AdvancedEnum that implements DescriptionProvider and extends VEnum

In PVTable I update all the code in order to get description by this way instead of PV instanceof DisplayProvider
I also use EnumDisplay to display Boolean value, because actually it display VBoolean.toString

Here is a screenshot on PVTable with Muscade OPCUA DataSource

[kasemir]

There are several ways to do this, so we can argue about this for a long time, but here's what I would do, and this has to be done in the VTypes:

DescriptionProvider is perfect as you have it.

Remove getDescription from the existing Display and instead have it implement DescriptionProvider, so it basically looks the same as before but with an inherited getDescription.
Have EnumDisplay also implement DescriptionProvider, so now the VEnum.getDisplay().getDescription() gets you the new info.

That would avoid adding new a AdvancedEnum, AdvancedBoolean and EnumProvider.

Note that IOCs use VEnum for boolean data. VBoolean is just true/false. Boolean records (bi, bo) use a VEnum with two options, that's how you can have labels for the two states beyond just true/false.
If your Muscade PVs have boolean data with added information like labels and now a description, use VEnum just like EPICS does.

Doing some intermediate work here until VTypes are updated means it has to be re-done in 2 weeks.

[shroffk]

@katysaintin with the previous PR #3228 merged I hope you are no longer stuck

I think I would like a bit more time on this issue primarily to understand the impact on the existing code.

[katysaintin]

@kasemir Thank you for your code review .
I can move my 2 classes AdvancedBoolean and AdvancedEnum in my Muscade project , but I thought it was useful to provide it for other datasource as an exemple.

For Boolean , I use Enum value instead, but some widget and rule use ONAM & ZNAM such as LED Boolean Button or boolean rule . If I use an enum it's become pv == 0 instead of !pv0 , that why I want to use VBoolean.

For ,boolean EPICS , I'm not sure, are bo and bi record are boolean or enum ? is EnumDisplay get ONAM & ZNAM ?

Anyway, thank you so much both of you @shroffk @kasemir for your help.

Katy

[katysaintin]

@katysaintin with the previous PR #3228 merged I hope you are no longer stuck

I think I would like a bit more time on this issue primarily to understand the impact on the existing code.

Yes No problem, I'm not stuck anymore, I can keep as it in my fork for instant.

[kasemir]

For ,boolean EPICS , I'm not sure, are bo and bi record are boolean or enum ? is EnumDisplay get ONAM & ZNAM ?

Yes, channels to bo and bi records use VEnum with two labels/choices in the EnumDisplay.