#13 Four Verbs, Every Control ​

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, which felt like cheating in the best way.

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. Four methods, and you now know the entire API.

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 vocabulary stays UI5's own, which is #4. The builder cannot be behind UI5, because it never knew what UI5 contains.

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. That last one catches the bug that used to be found by a colleague on a 2019 system, three weeks later.

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 name no control can build every control.