Views

About Views

_parent

Contains a reference to the parent template. This slot is
created when the view opens. Note that it's best to use the

Parent

function to access the parent view at run time, rather

than directly referencing the

_parent

slot.

stepChildren

Contains an array that holds references to each of the
template's child templates. This slot is created and set
automatically when you graphically create child views in
NTK. This slot is for children that you add to a template.

viewChildren

Contains an array that holds references to each of a system
proto's child templates. Because this slot is used by system
protos, you should never modify it or create a new one with
this name. If you do so, you may be inadvertently overriding
the children of a system proto. An exception to this rule
occurs for clEditView; you might want to edit the
viewChildren slot of a clEditView. See Table 2-1, "View
class constants," (page 2-2) in Newton Programmer's Guide
for details.

The reason for the dual child view slots is that the

viewChildren

slot is used by

the system protos to store their child templates. If you create a view derived from
one of the system protos and change the

viewChildren

slot (for example, to add

your own child templates programmatically), you would actually be creating a new

viewChildren

slot that would override the one in the proto, and the child

templates of the proto would be ignored.

The

stepChildren

slot has been provided instead as a place for you to put your

child templates, if you need to do so from within a method. By adding your
templates to this slot, the

viewChildren

slot of the proto is not overridden. Both

groups of child views are created when the parent view is instantiated.

If you are only creating views graphically using the Newton Toolkit palette, you don't
need to worry about these internal details. The Newton Toolkit always uses the

stepChildren

slot for you.

You may see either

viewChildren

,

stepChildren

, or both slots when you

examine a template at run time in the Newton Toolkit Inspector window. Child
templates can be listed in either slot, or both. When a view is instantiated, all the
child views from both of these two slots are also created. Note that the templates in
the

viewChildren

slot are instantiated first, followed by the templates in the

stepChildren

slot.

If you are adding child views in a method that will not be executed until run time,
you need to use the

stepChildren

slot to do this. If there isn't a

stepChildren

slot, create one and put your views there.