NAntContrib Help Task Reference <trycatch>

v0.85-nightly-2006-07-23

<trycatch>

[This is preliminary documentation and subject to change.]

Executes a set of tasks, and optionally catches a build exception to allow recovery or rollback steps to be taken, or to define some steps to be taken regardless if the tasks succeed or fail, or both.

The tasks defined in the <try> block will be executed in turn, as they normally would in a target.

If a <catch> block is defined, the tasks in that block will be executed in turn only if one of the tasks in the <try> block fails. This failure will then be suppressed by the <catch> block.

The message associated with the failure can also be caught in a property for use within the <catch> block. The original contents of the property will be restored upon exiting the <catch> block.

If a <finally> block is defined, the tasks in that block will be executed after the tasks in both the <try> and <catch> blocks have been executed, regardless of whether any task fails in either block.

Parameters

Nested Elements:

<try>

</try>

<catch>

</catch>

<finally>

</finally>

Examples

• <trycatch>
      <try>
          <echo message="In try" />
          <fail message="Failing!" />
      </try>
      <catch>
          <echo message="In catch" />
      </catch>
      <finally>
          <echo message="Finally done" />
      </finally>
  </trycatch>
      

  The output of this example will be:

  In try
  In catch
  Finally done
    

  The failure in the <try> block will not cause the build to fail.

• <trycatch>
      <try>
          <echo message="In try" />
          <fail message="Just because..." />
      </try>
      <catch property="failure">
          <echo message="Caught failure: ${failure}" />
          <fail message="Bad catch" />
      </catch>
      <finally>
          <echo message="Finally done" />
      </finally>
  </trycatch>
      

  The output of this example will be:

  In try
  Caught failure: Just because...
  Finally done
  Build failed: Bad catch
    

  Like the above, the failure in the <try> block does not cause the build to fail. The failure in the <catch> block does, however. Note that the <finally> block is executed even though the <catch> block failed.

• <trycatch>
      <try>
          <echo message="In try" />
          <fail message="yet again" />
      </try>
      <catch property="failure">
          <echo message="Caught failure ${failure}" />
          <fail message="Bad catch" />
      </catch>
      <finally>
          <echo message="Finally done ${failure}" />
      </finally>
  </trycatch>
      

  The output of this example will be:

  In try
  Caught failure yet again
  Build failed: Property 'failure' has not been set.
    

  The <echo> task in the <finally> block failed because the "failure" property was not defined after exiting the <catch> block. Note that the failure in the <finally> block has eclipsed the failure in the <catch> block.

• <trycatch>
      <try>
          <property name="temp.file" value="${path::get-temp-file-name()}" />
          <do-stuff to="${temp.file}" />
          <fail message="Oops..." />
      </try>
      <finally>
          <echo message="Cleaning up..." />
          <if test="${property::exists('temp.file')}">
              <delete file="${temp.file}" />
          </if>
      </finally>
  </trycatch>
      

  A more concrete example, that will always clean up the generated temporary file after it has been created.

Requirements