6 Replies Latest reply on Apr 7, 2008 6:22 AM by tom.baeyens

use generics in commands

porcherg Apr 3, 2008 3:47 AM

In the current pvm, command and command executor return Object.
With this approach, the user has to cast the result to use it.

Maybe we can change the command interface to a generic interface Command< T >, the execute method would return a T object.

public interface Command<T> extends Serializable {
 T execute(Environment environment) throws Exception;
}

This way, a user directly knows the class of the returned object.

What do you think of this modification ?

regards,
Guillaume

1. Re: use generics in commands

aguizar Apr 3, 2008 4:55 AM (in response to porcherg)
I was thinking about the same. In addition to the change you mention, we'd have to change the declaration of CommandService.execute() to something like:
public <T> T execute(Command<T> command)

Come to think of it, maybe only Command.execute() should be generic. I'm not quite sure the type parameter belongs to the entire class. It'd be interesting to evaluate both alternatives and see which one yields a cleaner interface.
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2. Re: use generics in commands

tom.baeyens Apr 3, 2008 8:42 AM (in response to porcherg)

Great idea !
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3. Re: use generics in commands

mvaldes Apr 3, 2008 8:52 AM (in response to porcherg)

Good, with this update i'm ok on changing the current XPDL extension APIs to use commands.

So, we will take a look on changing our proxy-interceptors approach by commands. This will allow us to still exposing APIs to end users (based on commands) + use commands directly as extension points.

regards,
Miguel Valdes
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4. Re: use generics in commands

tom.baeyens Apr 3, 2008 9:17 AM (in response to porcherg)

Awsome. Let me know if you need my help in making the command generics refactoring.
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5. Re: use generics in commands

porcherg Apr 7, 2008 6:21 AM (in response to porcherg)

I submitted the refactoring of Command interface to use generics.

I updated the Job and Message classes to use generics too (these classes implement Command).

regards,
Guillaume
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6. Re: use generics in commands

tom.baeyens Apr 7, 2008 6:22 AM (in response to porcherg)

perfect! thanks.
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