More of these options
will be discussed next as well as in the sections on generator de?¬?nition.
As mentioned, the main UI controls raised the need to specify some Python code
related to models. Three options were provided:
. Code could be added directly to selected model elements. This was considered
best for cases where just a few lines of code may be needed, like an optional
save validation function, which checks the form content before it is saved.
. Code could be reused from the library. Here, a model refers to code available
as a function, and the model only includes the parameters to be passed to the
function. The modeling language was made to allow both black-box and
white-box component libraries so that the modeler could also write function
code. To support code reuse from a library, the modeling language was
extended with a library concept added to the UI controls, navigation ?¬‚ows,
and Note dialog. If this property has a value, it is considered to refer to a
function. During code generation, the functions used are included in the
generated code.
. Code could be added to the generated code. For this purpose, protected regions
were de?¬?ned in the generated code. Basically, all previously de?¬?ned properties
LANGUAGE FOR APPLICATION MODELING 169
were also marked as protected regions so that they could be changed after
generation.
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