[e-lang] Hyper-printing

[Kevin Reid]

On Jan 27, 2007, at 2:27, Mark S. Miller wrote:

> 2) make it possible for an object's __printOn to effectively give  
> permission to the TextWriter-like out argument to make its provided  
> parts available from the rendering it is creating.
>
> Given E's guards and coercion system, I think we can make this work  
> by introducing a :HypertextWriter guard.

Clever! I also think this can work. I haven't thought about it very  
far though.

> An out that passes :HypertextWriter may provide such access, and it  
> may be further coerced by :TextWriter to create a TextWriter that  
> may be relied upon not to provide such access.

What guarantees would the HTW guard provide over no guard at all?

> I believe all this can be done without any changes to the existing  
> E system.

Yes, but to make it useful the system-provided objects need to use  
the HTW guard, or no guard, which would be a change.


Also, for good documentation of what the guards' significance is, the  
guards might need better names. TextWriter hasn't seemed a very good  
name to me, though HypertextWriter is an interesting extension that  
seems to make it make more sense in that context.

-- 
Kevin Reid                            <http://homepage.mac.com/kpreid/>