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Posted to users@tapestry.apache.org by George Christman <gc...@cardaddy.com> on 2012/08/21 05:27:38 UTC
Compiling error returning service interface in service locator
method
Hello, in my DMSServiceLocator.class, I have a method called getParser() with
a return type called Parser. I'm trying to return a service called
AutoMateParser with an Impl that extends Parser, however I'm' getting a
compiling error saying Parser is required, found AutoMateParser. When I
return new AutoMateServiceImpl() rather than my service interface, I receive
no compiling errors. It doesn't appear my getParser() method realizes
autoMateParser is of the same type. I tried casting AutoMateParser with
Parser, "return (Parser) autoMateParser;" which resolved compiling errors,
but received a cast exception. I'm wondering if anybody knows how to do
this. Thanks in advance.
below is a sample of my code.
AppModule
public static void bind(ServiceBinder binder) {
binder.bind(AutoMateParser.class, AutoMateParserImpl.class);
}
public class DMSServiceLocator {
@Inject
private AutoMateParser autoMateParser;
public Parser getParser() {
if(automate) {
return autoMateParser();
} else {
//Different data scrubber, but also extends Parser
return homenetParser();
}
}
}
public class AutoMateParserImpl extends Parser implements AutoMateParser {
protected Vehicle parseCar(String vehicleData) {
//some data scrubbing code
}
}
public class Parser {
//some csv line reader code
protected abstract Vehicle parseCar(String carData);
}
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Re: Compiling error returning service interface in service locator
method
Posted by George Christman <gc...@cardaddy.com>.
There's no interface to Parser, Parser is just an extended class located in
my service package along with my AutoMateParserImpl.
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Re: Compiling error returning service interface in service locator method
Posted by Joakim Olsson <jo...@unbound.se>.
Hi George,
It sounds like your Parser interface is located in one of Tapestrys
blessed packages (pages, components, mixins etc.)
/Joakim
On Tue, Aug 21, 2012 at 5:27 AM, George Christman
<gc...@cardaddy.com> wrote:
> Hello, in my DMSServiceLocator.class, I have a method called getParser() with
> a return type called Parser. I'm trying to return a service called
> AutoMateParser with an Impl that extends Parser, however I'm' getting a
> compiling error saying Parser is required, found AutoMateParser. When I
> return new AutoMateServiceImpl() rather than my service interface, I receive
> no compiling errors. It doesn't appear my getParser() method realizes
> autoMateParser is of the same type. I tried casting AutoMateParser with
> Parser, "return (Parser) autoMateParser;" which resolved compiling errors,
> but received a cast exception. I'm wondering if anybody knows how to do
> this. Thanks in advance.
>
> below is a sample of my code.
>
> AppModule
>
> public static void bind(ServiceBinder binder) {
> binder.bind(AutoMateParser.class, AutoMateParserImpl.class);
> }
>
> public class DMSServiceLocator {
>
> @Inject
> private AutoMateParser autoMateParser;
>
> public Parser getParser() {
> if(automate) {
> return autoMateParser();
> } else {
> //Different data scrubber, but also extends Parser
> return homenetParser();
> }
> }
>
> }
>
> public class AutoMateParserImpl extends Parser implements AutoMateParser {
> protected Vehicle parseCar(String vehicleData) {
> //some data scrubbing code
> }
> }
>
> public class Parser {
> //some csv line reader code
> protected abstract Vehicle parseCar(String carData);
> }
>
>
>
>
> --
> View this message in context: http://tapestry.1045711.n5.nabble.com/Compiling-error-returning-service-interface-in-service-locator-method-tp5715645.html
> Sent from the Tapestry - User mailing list archive at Nabble.com.
>
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Re: Compiling error returning service interface in service locator
method
Posted by Thiago H de Paula Figueiredo <th...@gmail.com>.
On Tue, 21 Aug 2012 11:26:21 -0300, George Christman
<gc...@cardaddy.com> wrote:
> Well I think I need to create an interface to ParserImpl, "Parser" and
> in the AutoMateParser interface extend Parser. However as I know now
> this is deff not an issue in how I'm using the services, but rather a
> George's Java skill issue lol. I've never written a Java program outside
> of Tapestry, so I
> sometimes easily confuse the two.
As we say here in Brazil, living and learning. :)
--
Thiago H. de Paula Figueiredo
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Re: Compiling error returning service interface in service locator
method
Posted by George Christman <gc...@cardaddy.com>.
Well I think I need to create an interface to ParserImpl, "Parser" and in the
AutoMateParser interface extend Parser. However as I know now this is deff
not an issue in how I'm using the services, but rather a George's Java skill
issue lol. I've never written a Java program outside of Tapestry, so I
sometimes easily confuse the two.
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Re: Compiling error returning service interface in service locator
method
Posted by Thiago H de Paula Figueiredo <th...@gmail.com>.
Just make getParser() return AutoMateParser instead of Parser. That's
object-oriented programming: if you have something that is defined by an
interface, use the interface. ;)
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Thiago H. de Paula Figueiredo
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Re: Compiling error returning service interface in service locator
method
Posted by George Christman <gc...@cardaddy.com>.
btw, my Parser.class is an abstract class. Sorry, I missed that in my
example.
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Re: Compiling error returning service interface in service locator
method
Posted by George Christman <gc...@cardaddy.com>.
The IDE suggest the cast because the AutoMateParser is not a sub-type of
Parser, only AutoMateParserImpl is. Just not sure how to make that work.
Any thoughts? Still new to binding, but should I be binding
AutoMateParserImpl to a Parser interface?
On Tue, Aug 21, 2012 at 8:02 AM, Thiago H de Paula Figueiredo [via
Tapestry] <ml...@n5.nabble.com> wrote:
> On Tue, 21 Aug 2012 00:27:38 -0300, George Christman
> <[hidden email] <http://user/SendEmail.jtp?type=node&node=5715660&i=0>>
> wrote:
>
> > Hello, in my DMSServiceLocator.class, I have a method called getParser()
>
> > with a return type called Parser. I'm trying to return a service called
> > AutoMateParser with an Impl that extends Parser, however I'm' getting a
> > compiling error saying Parser is required, found AutoMateParser. When I
> > return new AutoMateServiceImpl() rather than my service interface, I
> > receive
> > no compiling errors. It doesn't appear my getParser() method realizes
> > autoMateParser is of the same type. I tried casting AutoMateParser with
> > Parser, "return (Parser) autoMateParser;" which resolved compiling
> > errors, but received a cast exception.
>
> This is not a compiler error, but an exception instead. In addition, when
>
> you bind a service based on an interface, the instance of it you get is a
>
> proxy to the implementation class, not an instance of the service
> implementation, so this ClassCastException is expected. Why do you need to
>
> do this cast? This looks like a bad implementation decision in your code.
>
> --
> Thiago H. de Paula Figueiredo
>
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--
George Christman
www.CarDaddy.com
P.O. Box 735
Johnstown, New York
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Re: Compiling error returning service interface in service locator
method
Posted by Thiago H de Paula Figueiredo <th...@gmail.com>.
On Tue, 21 Aug 2012 00:27:38 -0300, George Christman
<gc...@cardaddy.com> wrote:
> Hello, in my DMSServiceLocator.class, I have a method called getParser()
> with a return type called Parser. I'm trying to return a service called
> AutoMateParser with an Impl that extends Parser, however I'm' getting a
> compiling error saying Parser is required, found AutoMateParser. When I
> return new AutoMateServiceImpl() rather than my service interface, I
> receive
> no compiling errors. It doesn't appear my getParser() method realizes
> autoMateParser is of the same type. I tried casting AutoMateParser with
> Parser, "return (Parser) autoMateParser;" which resolved compiling
> errors, but received a cast exception.
This is not a compiler error, but an exception instead. In addition, when
you bind a service based on an interface, the instance of it you get is a
proxy to the implementation class, not an instance of the service
implementation, so this ClassCastException is expected. Why do you need to
do this cast? This looks like a bad implementation decision in your code.
--
Thiago H. de Paula Figueiredo
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