Re: How to call createObject from within an OzoneObject?

On 8-5-2004 21:19, Leo Mekenkamp wrote:

> On Sat, 2004-05-08 at 18:41, Arjen van der Meijden wrote:
> 
>>Below in the example-code is a marker, and there the code fails, the 
>>Ozone-database doesn't know about any OzonePlugIn (actually it is the 
>>org.apache.struts.plugin.PlugIn it doesn't know about).
>>But even if this code would work, my object would reference the database 
>>"it is being created in" via some external, client-side, reference...
> 
> Why do you want to go through an extra class (OzoneAccess) from within
> an ozone object (FooImpl), when you can simply use this.database() from
> within an ozone object? 

Well, one reason is that I want uniform access to Ozone and as little 
knowledge of Ozone anywhere as possible, even in ozone objects.
The second is that I simply didn't know about this.database() I was 
looking for a getDatabase and overlooked database() ;)

> (btw: you cannot create an ozone object from
> within an ozone object ctor; the FAQ has more on this)

Ow, I forgot about that.

>>   public void init()
>>   {
>>     db = ExternalDatabase.openDatabase(...);
>>   }
> 
> 
> Initializing a static class variable within a non-static method without
> any == null test? No wander we guys from Leiden call you guys from Delft
> 'fietsenmakers'. ;-)

Then again, if you have a guarantee that the init-method will only be 
called at application-startup and the destroy-method only after 
application-shutdown, why bother about a never-true null-test ?
The only reason it can be null is because openDatabase may return null, 
and that results in an Exception (which I left out from this example).

Best regards,

Arjen



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