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| <h3>Breakpoints </h3> |
| <p>Breakpoints allow users to suspend the execution of a program at a particular |
| location. Breakpoints are typically shown in the UI along with the source |
| code. You can add an <a href="../reference/api/org/eclipse/debug/core/IBreakpointListener.html"><b>IBreakpointListener</b></a> |
| to an <a href="../reference/api/org/eclipse/debug/core/IBreakpointManager.html"><b>IBreakpointManager</b></a> |
| in order to be notified as breakpoints are added and removed. When a |
| breakpoint is encountered during execution of a program, the program suspends |
| and triggers a <b>SUSPEND</b> debug event with <b>BREAKPOINT</b> as the |
| reason. </p> |
| <p>Plug-ins that define their own debug models and launch configurations often |
| need to define their own breakpoint types. You can implement breakpoints |
| for your particular debug model by defining a class that implements <a href="../reference/api/org/eclipse/debug/core/model/IBreakpoint.html"><b>IBreakpoint</b></a>. |
| </p> |
| <p>Breakpoints are implemented using <a href="resAdv_markers.htm">resource markers</a>. |
| Recall that resource markers allow you to associate meta information about a |
| resource in the form of named attributes. By implementing a breakpoint |
| using markers, the debug model can make use of all the existing marker function |
| such as persistence, searching, adding, deleting, and displaying in editors.</p> |
| <p>Why is it important to know about markers when using breakpoints? When |
| you create a breakpoint type, you must also specify an associated marker |
| type. Every extension of <a href="../reference/extension-points/org_eclipse_debug_core_breakpoints.html"><b>org.eclipse.debug.core.breakpoints</b></a> |
| should be accompanied by an extension of <a href="../reference/extension-points/org_eclipse_core_resources_markers.html"><b>org.eclipse.core.resources.markers</b></a>. |
| This is best demonstrated by looking at the extensions defined by the Java |
| tooling for Java breakpoints.</p> |
| <pre><font color="#4444CC"><extension id="javaBreakpointMarker" point="org.eclipse.core.resources.markers"> |
| <super type="<b>org.eclipse.debug.core.breakpointMarker</b>"/> |
| </extension> |
| |
| <extension id="<b>javaExceptionBreakpointMarker</b>" point="org.eclipse.core.resources.markers"> |
| <super type="org.eclipse.jdt.debug.javaBreakpointMarker"/> |
| <persistent value="true"/> |
| <attribute name="org.eclipse.jdt.debug.core.caught"/> |
| <attribute name="org.eclipse.jdt.debug.core.uncaught"/> |
| <attribute name="org.eclipse.jdt.debug.core.checked"/> |
| </extension></font></pre> |
| <pre><font color="#4444CC"><extension point="org.eclipse.debug.core.breakpoints"> |
| <breakpoint |
| id="javaExceptionBreakpoint" |
| markerType="<b>org.eclipse.jdt.debug.javaExceptionBreakpointMarker</b>" |
| class="org.eclipse.jdt.internal.debug.core.breakpoints.JavaExceptionBreakpoint"> |
| </breakpoint> |
| </extension></font></pre> |
| <p>The debug plug-in defines a special type of marker, <font SIZE="2"><b>org.eclipse.debug.core.breakpointMarker</b>. |
| When you define a marker, you should declare it using this marker as a super |
| type. This allows the debug model to find all possible breakpoints within |
| a source file by searching for subtypes of its marker. In the example |
| above, the <b>javaExceptionBreakpointMarker</b> has a super type, <b>javaBreakpointMarker</b>, |
| whose super type is the <b>breakpointMarker</b>. The <b>javaExceptionBreakpoint</b> |
| (defined in the breakpoint extension) designates the <b>javaExceptionBreakpointMarker</b> |
| as its marker.</font></p> |
| <p><font size="2">What does all of this mean? When the debug code obtains |
| a source code resource, it can search for all markers whose super type is <b>org.eclipse.debug.core.breakpointMarker</b>. |
| Having found all of the markers, it can then use the plug-in registry to map the |
| markers to their associated breakpoint classes. In this way, the platform |
| debug code can generically find all breakpoint types that have been set on a |
| particular source file. </font></p> |
| <p> </p> |
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