[stringtemplate-interest] IAttributeRenderer and Type Inheritancein C#
Vincent DARON
vdaron at ask.be
Thu Oct 22 12:23:12 PDT 2009
Thanks all for your comments
I'm quite new to StringTemplate, the first need for that feature was
internationalization of Enumerations
(All Types starting with "My" are custom classes here to ease reading)
I simply try to do
StringTemplate.SetAttributeRenderer(typeof(Enum),new MyI18nEnumRenderer());
It did'nt works and I had to do
StringTemplate.SetAttributeRenderer(typeof(MyEnum1),new
MyI18nEnumRenderer());
StringTemplate.SetAttributeRenderer(typeof(MyEnum2),new
MyI18nEnumRenderer());
StringTemplate.SetAttributeRenderer(typeof(MyEnum3),new
MyI18nEnumRenderer());
...
The second need for that feature was for Formatting purposes
StringTemplate.SetAttributeRenderer(typeof(IFormatProvider),new
MyFormatProviderRenderer());
did'nt works either...
It's after that second problem that I looked into Sources and propose my
approach.
I do not think that it could be a speed problem, with a behavior like
mine, people using AttributeRenderer will probably use less Renderer.
The problem about priority is a little more embarrassing. Maybe using 2
lists instead of a Dictionary (Type and Renderer) ? People are adding
AttributeRenderer in the order they will be processed.
StringTemplate st = new ...
st.SetAttributeRenderer(typeof(MyClass), new MyRenderer());
st.SetAttributeRenderer(typeof(IMyInterface), new MyIRenderer());
st.SetAttributeRenderer(typeof(object), new MyDefaultRenderer());
st.ToString();
In this example the MyDefaultRenderer will be called for all Attributes
that are not of type MyClass and do not implements IMyInterface. It look
quite intuitive to me. The only difference is that the order of Setting
Renderer matters.
It's only suggestion :-) and any other ideas to solve these "problems"
are welcome.
Thanks,
Vincent
PS: Accessing source from trunk is possible ? How ?
Jonathan Buhacoff wrote:
> If it's integrated with the class renderers as I showed in my diff,
> there's a little extra work to do. On the other hand, most classes
> only implement handful of interfaces, and since this code doesn't do
> any string processing it will probably be fast enough.
>
> Or, if it's implemented as a separate map of renderers, then it will
> only slow down processing if the programmer has registered any
> interface renderers. But that seems a little messy to me, maybe more
> messy than the speed savings is worth.
>
> Finally, the other issue with interface renderers is priority - as
> proposed now, we have no control over which renderer will be found
> first, and if a class implements more than one interface with a
> registered renderer, the output will be non-deterministic. I think
> that's a bad thing.
>
> The way to control that would be to have a complete interface to
> manage the priority of interface renderers, or to have ST implement
> something like
> registerInterfaceAttributeRenderers(List<AttributeRenderer>
> renderers); so the programmer can specify the order of the
> renderers.
>
> So the loop would change to iterating through the registered interface
> renderers and checking if the value implements each one (and they
> would be in priority order).
>
> That makes things deterministic again, and would require the use of a
> list of interface renders separate from the map of class renderers,
> which means only people who use interface renderers would incur any
> performance penalty.
>
> I'm still trying to think of a case where this scheme would be better
> than wrapping everything with an adapter and registering a renderer
> for that, because automatically wrapping certain classes that
> implement an interface automatically is so easy to do by subclassing
> StringTemplate. I'm still thinking along the lines of
> internationalization, units of measure, stuff like that. Vincent can
> you provide a real world case?
>
>
> On Oct 22, 2009, at 9:45 AM, Sam Harwell wrote:
>
>
>> Hi Vincent,
>>
>> My first thought is this changes an O(1) algorithm that has to run for
>> every rendered item into an O(n) algorithm. I would have to run this
>> through the instrumenting profiler to make sure it isn't slowing down
>> the rendering process before I could include it. There are a few other
>> ways to approach the problem, but I'm not yet sure which one would
>> work
>> out best.
>>
>> Sam
>>
>> -----Original Message-----
>> From: stringtemplate-interest-bounces at antlr.org
>> [mailto:stringtemplate-interest-bounces at antlr.org] On Behalf Of
>> Vincent
>> DARON
>> Sent: Thursday, October 22, 2009 10:12 AM
>> To: stringtemplate-interest at antlr.org
>> Subject: [stringtemplate-interest] IAttributeRenderer and Type
>> Inheritancein C#
>>
>> Hi
>>
>> I would like to be able to register an IAttributeRenderer for objects
>> implementing an Interface.
>>
>> Part of current implementation of GetAttributeRenderer
>>
>> public virtual IAttributeRenderer GetAttributeRenderer( Type
>> attributeClassType )
>> {
>> IAttributeRenderer renderer = null;
>> if ( _attributeRenderers != null )
>> {
>> if ( !_attributeRenderers.TryGetValue(
>> attributeClassType, out renderer ) )
>> renderer = null;
>> }
>> // ...snip ... //
>> }
>>
>>
>> My proposal (untested, but should be ok)
>>
>> public virtual IAttributeRenderer GetAttributeRenderer( Type
>> attributeClassType )
>> {
>> IAttributeRenderer renderer = null;
>> if ( _attributeRenderers != null )
>> {
>> foreach(Type key in _attributeRenderers.Keys)
>> {
>> if(key.IsAssignableFrom(attributeClassType))
>> {
>> renderer = _attributeRenderers[key];
>> break;
>> }
>> }
>> }
>> // ...snip ... //
>> }
>>
>>
>> It will allow to register Attribute Renderer for objects implementing
>> interfaces
>>
>> RegisterAttributeRenderer(typeof(IFormatProvider), ...);
>>
>> Goot idea ?
>>
>> Second question, is it possible to have access to source using Source
>> Control (Subversion, Hg, Git, ...) ? It would be far easier to test
>> and
>> create patches.
>>
>> Thanks for answer/comments
>>
>> Vincent
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>
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