# 20130804 (Sunday, 04 August 2013)¶

Application code becomes easier. Instead of writing:

insert_layout = dd.FormLayout("""
event_type:25 type:25
subject
project company
""",window_size=(50,'auto'))


You can now write:

insert_layout = """
event_type:25 type:25
subject
project company
"""


Because insert_layout are now always initiated with that window_size when specified as a string.

I need to add application-specific rules for selecting the type of a welfare.notes.Note in Lino Welfare. To prepare this, I used the new app inheritance feature and added a new module lino_welfare.modlib.notes which extends lino.modlib.notes.

This was the first time that I extended a detail_layout, and it caused some subtle problems.

First I had to understand we must modify the original lino.modlib.notes.models.Notes class object by reassigning it’s detail_layout and insert_layout attributes. Subclassing the Notes class might look more clear coding style:

class Notes(Notes):

detail_layout = NoteDetail()

insert_layout = """
event_type:25 type:25
subject
project company
"""


But that would fail because the original module also defines subclasses of Notes, and we want also all subclasses to use our new detail_layout or insert_layout.

The above trick still works only with the lates version because one thing was to replace:

dl = getattr(cls,'detail_layout',None)


by:

dl = cls.__dict__.get('detail_layout',None)


But that wasn’t enough. The above change revealed another problem.

Actors without their own detail_layout will use the layout defined on their parent. But if this parent is overridden in another app, then they must install themselves as the datasource for this detail_layout.

E.g. the Persons table is defined in lino.modlib.contacts and overridden in lino_welfare.modlib.contacts. The welfare version does not override the insert_layout.