Hi Fred,
First, thanks for your help.
On 20/02/10 02:13, Fred wrote:
Henrique,
Something knows about Source, which can create a Config.
Something needs a Machine.
What knows about Source and can create a Config?
There is another class (lets call it ClassX) in Module B that knows
about Source and Config. Also, Machine objects are injected in this class.
A Machine is transitively dependent on this creation action, and so it
necessarily must be downstream of the creation of Source.
What expects a Machine, or more generally, what is the creation
lifecycle of Machine?
The ClassX from Module B creates, uses and discards Machine objects.
I've thought about a change in Module A while trying to answer your
questions. :)
Module A
--------
public class Machine {
@Inject @Assisted Config config;
@Inject PartFactory factory;
}
interface MachineFactory {
create(Config config);
}
class Part {
@Inject @Assisted Config config;
}
interface PartFactory {
create(Config config);
}
interface Config { }
There is a factory now to create Machine objects. The factory accepts an
Config object as parameter. ClassX now can create the Config object
using the ConfigFactory and the Machine using the MachineFactory.
Is this a good solution?
Cheers,
Henrique
-Fred
On Feb 19, 5:17 pm, Henrique Prange<[email protected]> wrote:
Hi all,
I'm facing a problem trying to use the injection mechanism between two
modules.
I have a Module A with the following classes:
Module A
--------
public class Machine {
@Inject Part part;
}
class Part {
@Inject Config config;
}
interface Config { }
Part is not public and is a requirement to build Machines. Part has a
dependency on Config. But the Config implementation is not defined in
Module A.
I have another Module B depending on Module A with the following classes:
Module B
--------
public class ConfigImpl implements Config {
@Inject @Assisted Source source;
}
interface Source { }
interface ConfigFactory {
create(Source source);
}
The ConfigImpl class requires a Source object to be instantiated. The
ConfigFactory must be used for this job, but the Machine class doesn't
know about the ConfigFactory interface. Also, doesn't make sense to
include the Source and ConfigFactory interfaces in Module A.
How could I solve this DI problem? I'm sure I have to rethink the design
of those classes. So, I would appreciate if you could provide any
directions.
Cheers,
Henrique
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