[Chicken-users] Cryptic SSAX error message

[Matt Gushee]

Hello, all--

OK, first of all, I have not forgotten that the SXML tools are full of black magic, etc. - no need to rehash that discussion. And so if it is not deemed feasible to fix the misbehavior I'm seeing, so be it. But I couldn't let this pass without saying something.

I was building a new blog with Coq au vin, which uses Civet to process templates, which in turn uses SSAX ... and one of my XHTML templates caused the following error:

csi> (load-template "base.html")

Warning: DOCTYPE DECL html http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd found and skipped
Error: XMLNS [4] for '
#\=
"'"

    Call history:

    civet-impl.scm:84: *template-path*     
    civet-impl.scm:439: make-pathname     
    civet-impl.scm:440: pathname-replace-extension     
    civet-impl.scm:441: template-cache-path     
    civet-impl.scm:88: *template-cache-path*     
    civet-impl.scm:89: template-path     
    civet-impl.scm:84: *template-path*     
    civet-impl.scm:89: make-pathname     
    civet-impl.scm:441: make-pathname     
    civet-impl.scm:442: update-cached-template?     
    civet-impl.scm:428: file-exists?     
    civet-impl.scm:429: file-exists?     
    civet-impl.scm:430: file-modification-time     
    civet-impl.scm:431: file-modification-time     
    civet-impl.scm:444: open-input-file     
    civet-impl.scm:447: ssax:xml->sxml          <--

This is obviously not very informative - but more than that, I found it misleading, because it refers to 'XMLNS [4]' - so I thought at first there was an error related to a namespace. That was not the case, as you'll see.

Fortunately, I kept a cool head and decided to check the file with xmlwf. Here's what that told me:

  $ xmlwf base.html
  base.html:16:17: not well-formed (invalid token)

Now that's a helpful error message. It turns out the problem was the inline _javascript_ in my template (which contained the <= operator). Since I was using the XHTML Transitional doctype, that's allowed per W3C specs, and it simply hadn't occurred to me that it was likely to result in non-well-formed XML.

I think someone who doesn't have extensive experience with XML and/or is trying to parse a file they did not create themselves might have no idea what to do with that SSAX error.

--

Matt Gushee