view-chain-layout

The layout of a view-builder chain

A chain is read far more often than it is written, and its layout is the only thing that makes it legible as the XML tree it stands for. Treat the indent as load-bearing, not as taste: it is the one place a reader can see where in the tree a line sits, so it has to be true.

These rules are identical in all three repositories — abap2UI5, abap2UI5/samples, abap2UI5/samples-controls. They were unified in one pass after a survey found the two sample corpora following opposite conventions for the same builder.

The seven rules

1. One call per line. Every ele( ), tag( ), a( ) and end( ) opens its own line with )->. A control never shares its line with its own attributes, nor with the container it opens.

2. Four spaces per level, everywhere. A child sits one level in from its container, a control's attributes one level in from the control. The same step in every file.

3. The closing paren rides with the arrow. Never a ) alone at a line end — carry it to the start of the next segment so it always reads )->. The whole view ends in a single )., not ) )..

4. end( ) stands alone in the column of the ele( ) it closes. That is what makes an ascent over several levels visible instead of hidden.

5. One attribute per line, v = / b = column aligned across a control's attribute block.

6. stringify( ) is a standalone final statement — client->view_display( view->stringify( ) )., never nested in the chain.

7. A wrapped t_arg list hangs under its FIRST element. When a _event( ) / follow_up_action( ) argument table runs over several lines, every continuation line starts in the column of the first ( … ) — not under the # of VALUE #(, which is three columns to its left and the drift this rule exists to stop:

   )->a( n = `close` v = client->follow_up_action( val   = client->cs_event-control_by_id
                                                   t_arg = VALUE #( ( `notificationList` )
                                                                    ( `removeItem` )
                                                                    ( `$event.oSource.getId()` ) ) )