twisted.web.template needs passthrough technique.

[jerub]

It is sometimes useful to do something along the lines of:

blob_of_rendered_html = someFunction()
return tags.html(tags.body(blob_of_rendered_html))

But it is not possible to get a str, or some kind of subclass of str, through _flattenString() or _flattenTree() without being modified.

[exarkun]

Passing through arbitrary strings is a good way to generate invalid output, potentially with security issues.

If you really need to put some HTML (or XML or what have you) into the result, you can parse it into tags and then put the tag tree into the output and it will be reflattened for you.

I think we should consider this feature carefully and not just assume it's something to include.

[glyph]

Replying to exarkun:

If you really need to put some HTML (or XML or what have you) into the result, you can parse it into tags and then put the tag tree into the output and it will be reflattened for you.

Also, if we implement template precompilation, you only need to pay this parsing cost once (assuming you cache the result). So perhaps we should do that first, then revisit this if there are still use-cases for it unsatisfied by that performance improvement?