#13 Four Verbs

The first view builder in abap2UI5 had one method per UI5 control. button( ), input( ), table( ) — hundreds of them, each with the control's properties as named parameters.

It was a good idea for a real reason. ADT code completion listed them. A developer who did not know the UI5 API could press Ctrl-Space in the backend and be shown what a control accepted, in ABAP, without leaving the editor. The frontend API had been imported into the backend tooling.

It also had a hard edge. A control the class had no method for could not be written at all. Every new UI5 control was a pull request, and a wrapper is a translation — it can be behind, and it can be wrong, in a way the browser only discovers at runtime.

The four verbs, and where each one leaves the cursor in the tree.

Its successor z2ui5_cl_ui5_view_builder has four verbs instead. ele opens an element and descends into it, tag adds a child and stays, a sets an attribute, end goes back up. Nothing in there names a control, which is exactly why every control is reachable — including the ones released last month and the ones nobody has wrapped.

The trade is honest: the completion list is gone. What replaced it is not nothing, though. The chain is still ABAP, so the compiler still checks it, and the linter checks the view against the real UI5 metadata before it ever reaches a browser — an unknown control, a misspelled property, a member that does not exist in the oldest supported release.

The completion list was a way to avoid reading the SDK. Coverage of the whole API is worth more than a shortcut around part of it.

Four verbs that know no controls can build every control.

Happy ABAPing! 🦖🦕🦣