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Subject: Re: Type of a generic class?
Date: Thu, 02 Aug 2012 20:08:29 -0700
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On 8/2/2012 4:27 PM, Donkey Hottie wrote:

> It is indeed kind of spooky and strange idea, after all what is so wrong
> about simple
>
>      String value = SystemProperties.getString("ParamName") ;
>
> It is OK, but I'm kind of toying with idea of strong typing of System
> Parameters: A Date can not be stored as Long or Double etc..


To do something like this, I'd arrange some implementation for the 
parameter:

class Parameter {
   public void processParam( String param ) {
      double d = Double.parse( param ); // or whatever...
      ...
   }
}

And then use a Map as Lew suggests or some other method of binding the 
Parameter class to the string "ParamName".

(You could, for example use Class.forName():
   Parameter proc = Class.forName( 
"my.project.parameter."+"ParamName").newInstance();

or you could use annotations:

@Parameter("ParamName")
class Parameter {...

or any other crazy thing you like.  It would probably be better than 
what you have now.)


> The back end of the system parameters is simply
>
> CREATE TABLE SystemParameters
> (
>      name varchar(64) not null primary_key,
>      value varchar(512)
> ) ;


I've written this table definition.  In fact it was 23 odd years ago, as 
in intern while still in college.  I don't know if it's good or bad 
practice, but it seems a common idea.