172 MOBILE PHONE APPLICATIONS USING A PYTHON FRAMEWORK
Guidance Rules Some of the domain rules were de?¬?ned to be checked only by
user choice. For this purpose, model checking reports were made, to be run when
needed or alternatively to be made available during modeling by showing a comment
element in the model. In other words, the comment element shows the result of
running a model-checking generator that reports on possible errors and gives guidance
if it detects that the model is incomplete. The latter was considered useful to guide
developers in the beginning as it showed some of the tasks needed to complete parts of
the design. The reports checked the following:
. If navigation ?¬‚ow was interrupted so that the application would stop before
exiting.
. If choices entered in the ?¬‚ow from Condition, List, or Pop-up had more than
one empty choice value or several identical values.
. If menu items started navigation ?¬‚ows that started more than one action.
Longer chains were considered to lead to navigation paths that are too dif?¬?cult
to understand by application users. Placing this rule in the guidance report still
allows one to make such designs (and thus applications also) so the rule was
more of a suggestion than an absolute rule.
8.3.3 Modeling Notation
The notation was created in parallel with the metamodel.
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