@Philippe
Guice uses an extensible way to convert Strings to
primitives/primitives wrappers/Enums and user defined types. If you
want to know more take a look at sisu guice-converter[1] (wrote by
Stuart that replied at this mail) or to mine Rocoto converters[2].
BTW my sample was just a dummy-silly way to expose the problem, I
wrote a piece of code that loads automatically tons of configurations
and I don't know which kind of data my team mates will plug :)
@Stuart
thanks for explanation, very appreciated. So now I have a question for
you, being more expert than me, and given the nature of the problem
I'm sure you can suggest me a valid suggestion :P
In Rocoto I've been maintaining a module[3] that extends the
com.google.inject.name.Names behavior and that's able to resolve
properties where users can define placeholders, like you do in
Ant/Maven, so users can define properties in the form:
a = ${b} ${c}
b = ${d|e} {f}
c = ${g} ${h|i}
...
where the pipe |, where present, separates the key name and the
default value. Now, the strategy I adopted is letting Guice resolve
the variables for me, so
I wrote a Provider<String>[4] that parses the properties, but that in
some cases forces me binding the properties to the provider... and
according the behavior you described, it obviously fails.
Do you have any suggestion how to realize a kind of workaround?
Many thanks in advance!!!
Simo
[1]
https://github.com/sonatype/sisu/tree/master/sisu-inject/guice-bean/guice-bean-converters/src/main/java/org/sonatype/guice/bean/converters/
[2]
http://code.google.com/p/rocoto/source/browse/#svn/trunk/src/main/java/com/googlecode/rocoto/converters
[3]
http://code.google.com/p/rocoto/source/browse/trunk/src/main/java/com/googlecode/rocoto/configuration/ConfigurationModule.java
[4]
http://code.google.com/p/rocoto/source/browse/trunk/src/main/java/com/googlecode/rocoto/configuration/resolver/PropertiesResolver.java
http://people.apache.org/~simonetripodi/
http://www.99soft.org/
On Fri, Nov 5, 2010 at 6:25 PM, Stuart McCulloch <[email protected]> wrote:
> On 5 November 2010 10:59, Simone Tripodi <[email protected]> wrote:
>>
>> Hi all guys,
>> I'm in trouble with a silly question but I hope you don't mind and
>> provide me a little help :P
>>
>> Given the simple POJO created by Guice:
>>
>> {{{
>> @Singleton
>> public class MyConfig {
>>
>> @Inject @Named("myconfig.autoclose") boolean autoClose(); // please
>> note the type
>>
>> // setter here
>>
>> }
>> }}}
>>
>> immagine the proeprty come from a text file, if in the module I bind
>> the property via:
>>
>> {{{
>>
>> binder.bindConstant().annotatedWith(Names.named("myconfig.autoclose")).to(myAlchemyObject.getStringValue());
>> }}}
>>
>> or, like in the com.google.inject.name.Names class:
>>
>> {{{
>> binder.bind(Key.get(String.class,
>>
>> Names.Named("myconfig.autoclose"))).toInstance(myAlchemyObject.getStringValue());
>> }}}
>>
>> things work well, the String will be successfully (if the value
>> matches) to boolean and the startup works well.
>>
>> Problems come when binding the String to a Provider<String>:
>>
>> {{{
>> binder.bind(Key.get(String.class,
>> Names.Named("myconfig.autoclose"))).toProvider(new Provider<String>()
>> {
>> public String get() {
>> return myAlchemyObject.getStringValue();
>> }
>> });
>> }}}
>>
>> the Injector raises an error:
>>
>> {{{
>> 1) No implementation for java.lang.Boolean annotated with
>> @com.google.inject.name.Named(value=myconfig.autoclose) was bound.
>> while locating java.lang.Boolean annotated with
>> @com.google.inject.name.Named(value=myconfig.autoclose)
>> for field at MyConfig.autoClose(MyConfig.java:XX)
>> }}}
>>
>> Any idea why?
>
> well looking at the convertConstantStringBinding method, it only considers
> String bindings which are constant - ie. those bound using bindConstant or
> toInstance - so your Provider binding is never considered for conversion
> I think this is a conscious design decision rather than an implementation
> detail - iirc this wasn't meant to be a full-featured type conversion system
> but something to help with basic configuration (hence constant values)
>>
>> Any suggestion will be more than appreciated, thanks in advance!
>> Simo
>>
>> http://people.apache.org/~simonetripodi/
>> http://www.99soft.org/
>>
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>
>
>
> --
> Cheers, Stuart
>
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