Component Defined with class(*ANCESTOR)

[jyoung]

While trying to figure out what I am going to do with my instance list issues, I extended VF_UM044O and the IDE dropped this into the code.

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function options(*DIRECT)
begin_com role(*EXTENDS #VF_UM044O) height(270) width(500)
define_com class(*ANCESTOR) name(#Pagination_Control) width(500)
define_com class(*ANCESTOR) name(#SinglePageList) height(220) width(500)

end_com

I have never seen a component defined with a class(*ANCESTOR). Can't find any documentation on this.

What is this? How does it work?

It looks like I can get access the underlying component VF_UI038O, but I can't see how that component is defined to see how this works.

Thanks,
Joe

[JamesDuignan]

Hi Joe,

"define_com class(*ANCESTOR)" is a component defined in the ancestor of the form, reusable part etc.

Usually you do not see the define_com for these, unless there is a change to the original definition, such as height, width, visibility etc.

For example:

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Begin_Com Role(*EXTENDS #PRIM_WEB) Theme(#SYS_THEME<MaterialDesignBlue>)

Define_Com Class(#PRIM_PHBN) Name(#Button1) Caption('Button1') Displayposition(1) Left(112) Parent(#COM_OWNER) Tabposition(1) Top(88) Height(48) Width(560)

End_Com

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Begin_Com Role(*EXTENDS #jdwebbase)

Define_Com Class(*ANCESTOR) Name(#Button1) Left(320) Width(352)

End_Com

regards,

James

[jyoung]

Interesting.

This seems to be a way to get a reference to a component in the ancestor without having to create a property for it? Kinda of like declaring a protected field in a C# or Java class?

I assume it is matched based on the Name?

Thanks,
Joe

[atostaine]

You could also create your own component that has that ancestor, add things, and then in this component use your new ancestor.

We did this extensively in VLF-win with command handlers. We added corporate logos, security routines whatever.

Can’t believe you haven’t seen that yet considering all the stuff your doing!

[jyoung]

Haha, nope never saw anything like it.

Anytime I had to do something like that I created properties or methods to get access to the ancestor components.

Good to know.

[MarkD]

The VLF objects designed to be extended by custom code are prefixed VF_AC (where AC = Ancestor class).
e.g. VF_AC007O (filter container) and VF_AC010O (Command handler).

There’s a VLF-ONE summary here https://docs.lansa.com/14/en/lansa048/i ... 8_6045.htm

and a VLF-WIN summary here https://docs.lansa.com/14/en/lansa048/i ... 8_6050.htm

The extending of VF_ prefixed objects that are not prefixed VF_AC (such as VF_UM044O) may mean your changes would not work in future versions.