There are issues with DOM itself:
- it doesn't report line numbers for elements, so error messages (other than parse errors) can't include them. Not very user- friendly :(

It does! Just need to disable libxml error reporting, so no warnings etc are generated, then pull the errors by hand.

But is there a way to get line number of any element if there were no parse errors? Things like invalid TALES expressions need to report line number, but aren't libxml's concern.

- non-validating parser can't support named entities (like  ), but users will expect them to work. Switching to validating parser is not an option, because it will reject incomplete HTML fragments and PHPTAL elements.

That is possible as well. Just need to tell DOM to resolve externals and validate against them (= doctype). I think we can expect people to write well-formed XML.

What DOCTYPE do you suggest? Document with XHTML DTD and TAL attributes won't be valid, so something else is necessary.

- parser decodes numeric entities and represents them as literal characters, possibly exposing encoding issues.

Eh? what do you mean. As long as the charset info is correct, everything is fine.

I meant that if someone didn't care about encoding, but just used named entities like £ would have to add/correct all necessary declarations. It's not a big problem.

IIRC libxml will even read a charset value from a meta tag in an XML document that it recognizes as XHTML.

Fortunately it does it only for HTML. XHTML user-agents must not read charset from <meta> element.

On a different topic, I really think we should use this DOM parser approach as the foundation for a completely new PHPTAL. There are some things that I think would be worth changing, for instance we should mandate the use of braces in function calls. That not only allows passing of arguments properly, it also eliminates the need of runtime evaluation of the type of the given element (array index, object property, object method). Not sure why it is as it is right now, but the "original" TAL uses braces for method calls, too, IIRC.

I'm pretty sure Zope's TAL does not require use of braces/parens. It even has nocall: modifier that prevents automatic calling of functions, which would be unnecessary if calls required special syntax.

However optional parentheses with arguments for function calls sound like a good idea. This can be done without a complete rewrite of PHPTAL :)

regards, Kornel

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