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The properties view

The properties view consists of a set of tabs, each of which supports editing a set of related features of the selected model element. For most elements there is an Appearance tab, with visual features only (like position and size), a Core tab, with all the semantic features (like name and type information) and a Behavior tab, with selected semantic features. The Core tab is based on the textual editing support that is generated from the underlying semantic model, while the Behavior tab complements the pure textual syntax with more usable form-based editing. We will only cover the Behavior tab here, since it includes the most important features.

The behavior tab

The behavior tab contains simple forms for editing selected features of the selected element(s). Each feature, like the type of a variable and the function of a connection, has its own form. In each form there is a dropdown that indicates the type of the current feature value and that may be used to select a different type. The form below the dropdown depends on the current type. Most dropdowns include a “None” type for no value, and an “Other” type, that utilises the same textual syntax as the Core tab. If you are interested in understanding the textual syntax, select a type and fill in its form, then select the “Other” type and inspect the corresponding text.

Types

Types play an important role, by limiting the values stored in variables, passed along connections and used and returned by functions. There are many kinds of types, the most important being classes, either Java or Ecore classes, and list of some element type. In addition, null values may be allowed or not.

A class (type) is indicated by its name (including package prefix), and appending a + or - sign allows or disallows null values. A list type allowing from <n> to <m> values of some element type is written as the element type followed by [<n>..<m>]. If one or both of <n> and <m>, are omitted, they default to 0 and unlimited, respectively. E.g. an unlimited list of strings is written as String[..].

Functions

Functions are used for many purposes, and is the most important property of connections, computations and gates. There are many kinds of functions, e.g. type checking and conversion, getting and setting properties, transforming and filtering lists and more generic script functions.




2007/11/07 01:11, Hallvard Trætteberg
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