[stringtemplate-interest] format option implementation details

[John Snyders]

> > To make use of format you must create a renderer that implements  
> > AttributeRenderer. AttributeRenderer is enhanced to add the  
> > toString method that takes a formatName. (Now that I think of it,  
> > for backwards compatibility perhaps we should create a new  
> > interface such as AttributeRendererEx? so that existing renderers  
> > don't break)
> 
> Well, at least the compiler will tell them and it's a quick  
> change...I'd prefer to force this "upgrade" probably.

OK

> > There are two interesting things to be aware of with the format option
> > 1) If format is applied to a template rather than an attribute an  
> > intermediate string must be created so that the format can be  
> > applied to the result of the template. This is not unlike when a  
> > template is used in an indirect property (i.e. $attribute.({<some  
> > template})$
> 
> Good point.  format forces early evaluation. :)
> 
> > 2) if the renderer is associated with type String then it is  
> > possible for the value of an attribute to be rendered twice. This  
> > will only happen if the format is applied to a template rather than  
> > an attribute.It happens because the String attribute is rendered  
> > and written as part of the value of the template expansion then the  
> > format is applied to the String value of the template. Now that I  
> > think of this more it may be a bug. I'll look into it.
> 
> Just an efficiency thing.

Not just efficiency. I depends on if your rendering is idempotent.
I had a renderer that escaped quotes " --> \". Now I end up with \\"


> > I need to do more testing but here is what I have done so far. If  
> > someone wants the whole file let me know and I can send it but it  
> > has other changes as well.
> 
> I'll do my own implementation, using your excellent work as a guide!   
> May I paraphrase your text here for the manual?

no problem