Single type argument version of Tag

The current API provides two versions of Tag.

• Tag
• Tag<M,T>

This issue suggests that we add a third type that takes a guess at which Mapper class to use based on a single type argument for the CLR type to use. i.e. Tag<T>

Some discussions where this was discussed:

• https://github.com/libplctag/libplctag.NET/issues/28#issuecomment-653854167
• https://github.com/libplctag/libplctag.NET/issues/153

What needs to be decided?

• What should the mappings be between CLR type and Mapper types.

[jkoplo]

I took a quick spin through it, but your other comment jogged my memory.

If we only specify the CLR type, how do we know what the PLC type is to create the tag? (Since they aren’t 1-to-1). Or can we actually get by without knowing that?

Other than that, in terms of implementation I was thinking of using a dictionary or even a factory-pattern to get the mapper. That has the benefit of getting the case structure out of the class and allowing for runtime changes (adding custom mappers) with the trade-off of increased complexity. If we didn’t want to DI the lookup, then we’d have to make it a static. That being said, defining it in code is more or less a static anyway.

The other route would be to go toward an actual factory-pattern for tags. I end up implementing that in my local code anyway. Create a TagFactory and set PLC path/params/etc and then just use it to instantiate tags with a Type and Name. Each factory instance could hold an instance of the lookup that it uses to DI. At that point, we could just pass the proper mapper to the Tag and take that concern away from the Tag class. Thoughts?

[TheFern2]

@jkoplo how do you call function to create tag, read write value from another class?

Please don’t necro threads. This question has nothing to do with this discussion.

Post questions to libplctag forum or open another issue with your question. https://github.com/libplctag/libplctag#libplctag-forum