[platform-ant-dev] Copying existing configs to use as project builders

[Jared Burns <jared-eclipse@xxxxxxxxx>]

Bug 16574 (<http://bugs.eclipse.org/bugs/show_bug.cgi?id=16574>) covers a 
feature we'd like to add whereby the user would be able to add an existing 
launch configuration as an external tool project builder.

Adding an existing config ("by reference") is not technically feasible, but 
we'd like to let the user copy ("by value") an existing config to be used as 
a project builder.

So we need a way to take a config of the type that shows up in the launch 
config dialog and create a new "builder config" of the appropriate type.

For example, if the user wants to copy an Ant config to use as a project 
builder, we need to take a config of type 
"org.eclipse.ant.AntLaunchConfigurationType" and copy the attributes into a 
new config of type "org.eclipse.ant.AntBuilderLaunchConfigurationType".

The only decent way I can think to do this is to create an extension point 
that would allow external tool writers (like us) to explicitly state what 
builder config type should be used when copying a normal config.

Extensions would look something like so:
<extension point="org.eclipse.ui.externaltools.configurationDuplicationMap">
  <configurationMap
    type="org.eclipse.ant.AntLaunchConfigurationType"
    builderType="org.eclipse.ant.AntBuilderLaunchConfigurationType">
  </configurationMap>
  <configurationMap
    type="org.eclipse.ui.externaltools.ProgramLaunchConfigType"
    builderType="org.eclipse.ui.externaltools.ProgramBuilderLaunchConfigType">
  </configurationMap>
</extension>

Good/bad/ugly?

- Jared