Ant trycatch usage

We recently spent much time debugging a build issue that resulted from an Ant-Contrib <trycatch>. Due to a missing <catch> element, an error that occurred within the <try>element went unreported.

After some investigation, we’d like to suggest the following usage:

  • Add a “reference” attribute to the <trycatch>element
  • Add a <catch> element to the <trycatch>block in order to:
    • Create a <property>based on the exception reference
    • Create another <property> containing a formatted message based on the exception <property>
    • <echo>the message, which will appear where the error occurred in the Ant output
    • <fail> specifying the message, which will ensure that a stack trace (of sorts) will appear at the end of the Ant output
<trycatch reference="exception_ref" >
			... some risky Ant work ...
			<property name="exception" refid="exception_ref" />
			<property name="message" value="Error in trycatch block:${line.separator}${exception}" />
			<echo message="${message}" />
			<fail message="${message}" />
			... optional ...


The <trycatch> element also supports a “property” attribute that will ‘receive the message of the exception’, and as such loses the stack information. By contrast, the “reference”attribute points to the exception object itself, including the stack information.


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