The Metamodel Browser is a tool for viewing and editing modeling language specifications. Through the Metamodel Browser the modeling language developer has access to all modeling languages available in currently open projects, along with the types they contain. To open a Metamodel Browser, either activate its tab on the MetaEdit+ Launcher or select Metamodel | Metamodel Browser from the menu.

As Figure 7–1 illustrates, the Metamodel Browser is similar to the other browsers of MetaEdit+. The left-hand list shows all the projects that are currently opened in the MetaEdit+ client. If the project you want is not visible, you can open it explicitly from the list’s pop-up menu.

The middle list shows all the available graph types, filtered by the projects selected in the left-hand list.

The list on the right shows the types contained in the graph type that is selected in the middle list. You may determine which element types are visible in the right hand list from the pull-down list labeled Show. In Figure 7–1, all object types of the WatchApplication graph type are shown.

The Metamodel browser also allows you to view the graph types by their explosion and decomposition hierarchies, by viewing both hierarchies simultaneously, or according to the subtype structure of the graph types. This viewing option can be selected from the Tree pull-down list.

As in other browsers of MetaEdit+, you can choose the default project for graph and type creation, and set wildcard string filters for the middle and right-hand list contents.

In addition to browsing the modeling language specifications, you can open them for editing with the metamodeling tools, and view more detailed information about type usage.

Editing is carried out in the metamodeling tools described earlier (Graph, Object, Relationship, Role and Property tools). To open these tools select the type from the list and double click it, or alternatively choose Edit Type from the component’s pop-up menu. This opens a metamodeling tool for that type. To edit the symbol, select Edit Symbol from the popup menu.

The pop-up menu for a type also includes Type Info, which opens a Type Info tool showing which types use this type, and which types it uses. The Type Info tool is similar to the Info tool for design data, and is illustrated in Figure 7–2.

The Type Info tool has three fields. The label at the top shows in which project the type is stored. The upper list shows which types use this type, along with the project where they are defined, and the function of this type within the using type. The lower list shows which types are used by this type, along with the project where they are defined.

In Figure 7–2 a Type Info tool has been opened for State [Watch]. This type is defined in the Watch project. It is used in the WatchApplication diagram in the Watch project. State [Watch] itself uses other types as its properties, e.g. the Name [Watch] property type, which is defined in the Watch project.

More information about a type shown in the Type Info tool can be seen by selecting that type. From the pop-up menu you can then choose Info to open it in its own Type Info Tool, or double click the type to open it in the appropriate metamodeling tool.