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| Project-scoped preferences |
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| <H2> |
| Project-scoped preferences</H2> |
| <P > |
| In <a href="runtime_preferences.htm">Runtime preferences</a>, we looked at the infrastructure for defining and |
| storing preferences with different scopes. We also saw that the |
| <a href="../reference/extension-points/org_eclipse_core_runtime_preferences.html"><b>org.eclipse.core.runtime.preferences</b></a> |
| extension can be used to define additional scopes for preferences. The platform resources plug-in defines its own |
| preference scope, called "Project," in order to define project-scoped preferences. Project-scoped preferences are stored in a file located |
| inside the project. This makes it easy to store a set of preferences and exchange them with other users using |
| resource-oriented mechanisms such as a version control system. |
| </p> |
| <h3>Specifying the scope</h3> |
| |
| <p>The definition for new scopes is pretty simple. The plug-in defines the name of the scope, as well as the class |
| that implements it. The resources plug-in defines the project scope |
| as follows: |
| </p> |
| <pre> <extension id="preferences" point="org.eclipse.core.runtime.preferences" name="preferences"> |
| <scope name="project" class="org.eclipse.core.internal.resources.ProjectPreferences"/> |
| </extension> |
| </pre> |
| <p>The specified class must implement the |
| <b><a href="../reference/api/org/eclipse/core/runtime/preferences/IScope.html">IScope</a></b> interface, which means |
| it must be capable of creating preference nodes for the scope. |
| </p> |
| |
| <h3>Project-scoped preference nodes</h3> |
| |
| <p>Since the project scope for preferences is not one of the standard runtime scopes, the node representing a project-level |
| preference must be obtained specifically. From the root preference node, you must navigate to the project-scoped |
| preference. This can be achieved using the <b>ProjectScope</b>: |
| </p> |
| <pre> IScopeContext projectScope = new ProjectScope(MyProject); |
| </pre> |
| <p>Once the project scope for a particular is project is found, the preference values can |
| be obtained using the same mechanisms seen earlier. Preferences are named using the string name of the |
| preference. The names are qualified with another string (often a plug-in id) that qualifies the namespace |
| of the preference. The following snippet gets a preference node from the project scope. You'll notice that once |
| the correct scope is obtained, working with the nodes is no different than with nodes from other scopes. |
| </p> |
| <pre> ... |
| Preferences projectNode = projectScope.getNode("com.example.myplugin"); |
| if (projectNode != null) { |
| value = projectNode.getBoolean("MyPreference", "true"); |
| //do something with the value. |
| } |
| ... |
| </pre> |
| <p>To save the value to a file in the project, the node is flushed. The resources plug-in handles the logistics |
| for managing the project-level preferences file. |
| </p> |
| <pre> projectNode.flush(); |
| </pre> |
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