[slf4j-dev] Static binding...

[Joern Huxhorn]

Hi Ceki,

I asked it here because the static binding of the actual logging  
implementation is a seemingly important SLF4J feature. My guess is  
that this was important when SLF4J was still using  
StaticLoggerBinder.SINGLETON and now it's only there for historical  
reasons.

I'm interested in those subtle differences. I'm not aware of any.

Also, I'm asking the question because I've gone completely insane.

I started an slf4j-redesign at
http://github.com/huxi/slf4j/tree/slf4j-redesign/slf4j-n-api/

You were right, btw. My initial idea wouldn't have worked in case of   
Logger deserialization. But I avoided that problem, now.

My plan is the following (as documented in NewLoggerWrappingOld):
It is used if a binding does not implements org.slf4j.n natively, i.e.  
the class org.slf4j.n.impl.StaticLoggerBinder does not exist. In that  
case, a fallback ILoggerFactory implementation is used that returns an  
instance of this class containing the logger returned by  
org.slf4j.LoggerFactory.getLogger(..).

I've not finished the implmenetation (LoggerFactory isn't done yet)  
but the n.Logger interface looks as planned and the implementation of  
AbstractLogger NewLoggerWrappingOld and OldLoggerWrappingNew are more  
or less done.

The LoggerFactory implementation, as planned, would require me to get  
the singleton using
ILoggerFactory factory=(ILoggerFactory)  
Class 
.forName 
("org 
.slf4j 
.impl.StaticLoggerBinder").getMethod("getLoggerFactory").invoke(null);

That's why I'm asking...

Regards,
Joern.

On 26.11.2009, at 17:55, Ceki Gülcü wrote:

> Hi Joern,
>
> Well, it's more of a java question than slf4j. The difference is  
> between direct method call and a method call via reflection. The  
> latter is known to be a bit slower and is also harder to read. There  
> might also be subtle class loader differences.
>
> Joern Huxhorn wrote:
>> I was wondering if there is a real substantial difference between
>> a) ILoggerFactory  
>> factory=org.slf4j.impl.StaticLoggerBinder.getLoggerFactory();
>> and
>> b) ILoggerFactory factory=(ILoggerFactory)  
>> Class 
>> .forName 
>> ("org 
>> .slf4j 
>> .impl 
>> .StaticLoggerBinder").getMethod("getLoggerFactory").invoke(null); I  
>> mean, are the classes resolved any different?
>> Beside a compile-time error in case of a) if the class is missing,  
>> of course.
>> Regards,
>> Joern.
>
> --
> Ceki
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