We have a large build.xml file with some tasks repeated verbatim in multiple targets -- such as a long-winded <echo>, which updates the log-file(s) with contents of an object:
<echo file="foo.log" message="${run.name} completed with status ${run.status}. Errors: ${run.errors}, warnings: ${run.warnings}, processed ${run.processed}"/>
Can this be turned into something like <logrun file="file.log" run=${run}"/> -- in the XML? That is, without us writing Java-code to implement the new logrun-task?
The short answer is yes, using the Ant <macrodef> task.
Something like this:
<macrodef name="logrun">
<attribute name="file"/>
<attribute name="name"/>
<attribute name="status"/>
<attribute name="errors"/>
<attribute name="warnings"/>
<attribute name="processed"/>
<sequential>
<echo file="@{file}"
message="@{name} completed with status @{status}. Errors: @{errors}, warnings: @{warnings}, processed @{processed}${line.separator}"/>
</sequential>
</macrodef>
<logrun file="foo.log" name="foo.name" status="foo.status" errors="foo.errors" warnings="foo.warnings" processed="foo.processed" />
Notice the way named macro parameters are referenced in the "body" of the macro using @-prefix. I added a ${line.separator} at the end of the message parameter, so that the line written to the file is terminated. You might want to use append="true" in the echo task, in order that the file is not completely overwritten each time the macro is called.
A macro might cater for all your attribute edge cases, depends how complex they are.