Designing for reusability – Apple WebObjects 3.5 User Manual
Page 106
Chapter 6
Creating Reusable Components
106
that were linked in to the application executable for a component with that
name. For example, applications written entirely in WebScript use the default
application executable,
WODefaultApp
. This executable is linked to the frameworks
WebObjects.framework
and
WOExtensions.framework
, so any components defined in either
of these two frameworks can be used in a scripted application.
Designing for Reusability
Here are some points to consider when creating reusable components:
•
Make sure that your reusable component generates HTML that can be
embedded in the HTML of its parent component.
A reusable component should be designed to be a “good citizen” within
the context in which it will be used. Thus, for example, the template file
for a reusable component should not start and end with the <HTML> and
</HTML> tags (since these tags will be supplied by the parent
component). Similarly, it is unlikely that a reusable component’s template
would contain <BODY>, <HEAD>, or <TITLE> tags.
Further, if you intend your component to be used within a form along with
other components, don’t declare the form (<FORM...> ... </FORM>)
within the reusable component’s template file. Instead, let the parent
component declare the form. Similar considerations pertain to submit
buttons. Since most browsers allow only one submit button within a form,
putting a submit button in a reusable component severely limits where it
can be used.
•
Guard against name conflicts.
Reusable components are identified by name only. See “Search Path for
Reusable Components” (page 105). Those that reside within a particular
application’s application directory are available only to that application.
Those that reside in a framework (for example,
WOExtensions.framework
) are
available to all applications that link to it. Suppose you have a component
named NavigationControl in your application and one of the frameworks
that your application links to also has a NavigationControl component.
Which one will be used in your application? The result is unpredictable.
Reusable component names need to be systemwide unique. Consider
adding a prefix to component names to increase the likelihood that they
will be unique.