Musings

1. If you’re using MySQL, you’ll have to add a column to store the text filter to apply to each comment.

   alter table mt_comment add column comment_convert_breaks varchar(30);

2. You’ll need this plugin and, if you don’t already have it, the Compare plugin.
3. Next, you’ll need to run this patch on your MovableType installation (patch < CommentTextFilters.patch). If you’re using ThreadedComments, use this version of the patch instead. Those were for MovableType 2.6x. MovableType 3.1x users should download either CommentTextFilters3.14.patch or ThreadedCommentTextFilters3.14.patch .

4. Now, alter your Comment-Entry form to add

    <label for="convert_breaks">Text Filter:  </label>
      <select id="convert_breaks" name="convert_breaks">
    <MTTextFilters>
       <option value="<MTFilterKey>" <MTIfEqual a="[MTFilterKey]" b="[MTDefaultCommentFilter]">selected="selected" </MTIfEqual> > <MTFilterLabel> </option>
    </MTTextFilters>
      </select><br />

   and add the line

     <input type="hidden" name="convert_breaks" value="<$MTCommentPreviewTextFilter$>" />
   

   or, better yet, the selector

     <label for="convert_breaks">Text Filter: </label><br />
     <select name="convert_breaks" id="convert_breaks">
   <MTTextFilters>
         <option value="<MTFilterKey>"  <MTIfEqual a="[MTFilterKey]" b="[MTCommentPreviewTextFilter]">selected="selected"</MTIfEqual> ><MTFilterLabel></option>
   </MTTextFilters>
     </select><br />

   to the form in your Comment-Preview Template and your Comment-Error Template.

5. If you’re using my Comment Validation setup and are using my itex2MML Text Filter, you’ll need to get an updated version of my patch to MTValidate.

6. Finally, you may need to adjust the Sanitize specification for your blog. Comments are run through Sanitize, which removes all of the HTML elements or attributes that you do not specifically allow. If you want commenters to be able to post MathML content, using itex2MML, you need to enlarge this set. My Sanitize specification now reads

   div class id,bdo,* dir xml:lang title,span,p,br/,a href target,
   abbr,acronym,b,u,i,strong,em,ul,ol,li,dl,dt,dd,sup,tt,
   sub,pre,blockquote,code,math xmlns display,
   mo lspace rspace fence separator stretchy maxsize minsize,
   mi mathvariant,msub,msup,msubsup,mfrac linethickness,mn,
   mstyle scriptlevel mathvariant mathcolor mathbackground
   displaystyle,mtext,mspace width height depth,msqrt,
   mmultiscripts,mprescripts/,none/,mroot,mphantom,
   merror,mover,munder,munderover,maction actiontype
   other selection,mtable align columnalign rowalign
   equalrows equalcolumns columnspacing rowspacing
   columnlines rowlines frame,mrow xmlns:xlink xlink:type
   xlink:href,mtr rowalign columnalign,mtd rowspan 
   columnspan rowalign columnalign, mpadded width

   where everything in red is a MathML tag or attribute. Since this is longer than 255 characters, I had to change blog_sanitize_spec from varchar(255) to text in my MySQL database.

Update: I forgot to say that I’ve releases a new version of my itex2MML plugin. This one strips carriage-returns, as the (Unix-based) itex2MML converter expects new lines to be delimited by the linefeed character. You’ll definitely need the new version to use that text filter in comments.

Update (5/30/2003): Yuan-Chung Cheng has a nice article on daisy-chaining Text Filters, for even more options. As an example, I’ve added a Textile+itex2MML Filter to this blog.

Update (6/13/2003): A tweak to the CommentPreview template. Added the selection attribute for <maction> to the Sanitize spec. I need to think about the other attribute for <maction>, which is officially deprecated in MathML 2.0, but is still used by itex2MML.

Update (2/6/2005): Patches which work with MT 3.1x and a small tweak to the sanitize spec.

P.S.:In case you were wondering at my curious obsession with Comment Validation, this is the reason why. It’d be foolish to open up this blog to MathML comments without some serious bullet-proofing.