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From Oliver Heger <oliver.he...@oliver-heger.de>
Subject Re: [lang] VariableFormatter - pre 2.2
Date Wed, 02 Aug 2006 19:03:24 GMT
Stephen Colebourne wrote:
>>> For example "There were ${number} characters", would return the 
>>> object matching the ${number} substitution, and dropping the rest of 
>>> the text!
>>>
>>> Perhaps you can point to an exact use case?
>>>
> Oliver Heger wrote:
>> Your analysis is correct. The idea was that you can have specialized 
>> resolver implementations that inherently work on objects, e.g.
>>
>> - a constant resolver, which interprets the variable name as a name of 
>> a static field of a class, e.g.
>> ${my.package.MyClass.MY_CONSTANT} would return the value of the 
>> constant field.
>>
>> - an expression resolver, which could be passed an expression in a 
>> language like JEXL and would calculate the result.
>>
>> Of course if the string passed to the substitutor contains other text 
>> elements or variables, you have no choice than converting the result 
>> to text. But if only a single variable is to be processed, the result 
>> can be an arbitrary type.
> 
> Sounds a bit [configuration] specific to me.
> 
> However, we could add a singleVariableName(String) method which would 
> check for the special case where the whole string was a variable.
> 
> We could also have a variableNames(String) method which returns the top 
> level variable names in the string.
> 
> Not sure how useful either of these would really be though.
> 
> What might be more useful, would be to change the method signature of 
> resolveVariable() to take the StrBuilder start pos and current variable 
> start and end. That would effectively provide subclasses with much more 
> detailed events about the variables.
> 
> So, pre 2.2 - I'd suggest
> a) alter resolveVariable()
> b) extract VariableFormatter interface to be StrLookup abstract class
> c) agree class name (is anyone not OK with StrSubstitutor?)
> 
> Stephen
> 
a) and b) is fine with me. The discussion about the class name I will 
leave to you native speakers ;-)

Oliver

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