Code highlighting?

[radiantmatrix]

Update 2004-10.Oct-19: Due to many concerns, both public and private, this proposal has been withdrawn.

I've forgotten where, now, but I visited a site last week with some example Perl code listings. The code was highlighted much as it might be in Komodo, Emacs, Vi, &c..

Our <code> tags are used mostly for Perl code, but sometimes for other forms of text. So, if the Monestary added code highlighting support, we'd need to have a way of specifying what counts as "Perl code" and what is just a block of preformatted text (without using the <pre> tags. The two that pop into my head are an attribute:

# I've needed to escape slashes in HTML tags...

<code type='perl'>print("This is perl code");<\/code>
# or
<code type='noperl'>This is output, or some non-perl code<\/code>

Or a special tag:

<pcode>Perl code </pcode>
#or
<notcode>Not code </notcode>

Only one of either pair would need to be implemented: e.g. if <pcode> tags were used, the default <code> tags would be non-perl code. And vice-versa.

I am willing to apply my less-than-saintly coding skills to do the work, but I'm curious before I start: is this something the Monestary would like? If so, how should it work? Restrictions, ideas?

[demerphq]

Personally i am in favour of something like this. BUT its not so straightforward, and there are legitimate issues such as load, and theme sensitive color schemes that need to be addressed for such an endeavour. Presumably we could use the HTML output form of Perltidy, but Perltidy is a known resource hog.

You should have a look through the PMD archives as this subject comes up fairly regularly and the comments made before will still be relevent now.

[Your Mother]

theme sensitive color schemes that need to be addressed for such an endeavour...

This can be addressed by doing the coloring in CSS; post processing (using the Syntax::Highlight::Perl keywords for classes):

<code class="perl"><span class="Directive">print</span> <span class="Quote">"</span><span class="String">Hello world...

Then everything is still black unless you have a style sheet with code.perl > .Directive { ... } etc. and each style could have its own code styles companion.

As much as I'd like to see it, it does seem like a big headache, it would mostly only improve readability of longer code, and even using the faster methods available, it would slow things down a bit.

Oh, and this node, already listed below by cchampion doesn't mention that Perl::Tidy is customizable with its "formatter" arg to perltidy() though it's difficult to use.

[kutsu]

This has been brought before (I can remember syntax highlighting of code in perlmonks forums and Feature Request: Adding Colors to Source Code at least), so you might look there for monk's opinions. I also remember Jaap having a javascript solution for this, though I can't remember where it is it's (Client side) Perl Syntax Highlighter. As for me, I have syntax highlighting turned off on my PC's and never have liked it.

[PodMaster]

(Client side) Perl Syntax Highlighter (Re: (Client side) Perl Syntax Highlighter)
syntax highlighting of code in perlmonks forums
Code Highlighting in the code tag

[cchampion]

As you can see form the links that other monks have provided, syntax highlighting for PerlMonks is not popular enough for the pmdev to implement such feature.

For your personal consumption, though, you may try Vim for PerlMonks nodes and On-the-fly all-languages syntax highlighting.

[radiantmatrix]

Right that the pmdev staff should not be saddled with it. But, it seemed that there were a few people who would enjoy it. Also, it would be very helpful for new SoPW to be able to understand some of the "quickie code" laid down by the Monks.

That's why I'm offering to do the code -- I couldn't promise that it would be done quickly, but it would be a great exercise. As long as there isn't significant opposition to the idea, and as long as users could turn it off in their preferences, it is something I'd like to do. That makes this particular discussion slightly different than previous nodes.

My primary questions, then, are:

• Are there any objections to implementing this?
• Would the pmdev team roll the patches in, assuming they were done well, etc, etc.?
• If it were done, how should it be done? IOW, what would make the monestary comfortable with the idea?

[eric256]

The problem is that this isn't something you can realy opt-out of. For instance if you post code, the server should realy do the HTML markup for highlighting then (no reason to do it over and over). If the next person doesn't want highlighting then they don't use the CSS to highlight it. However even though that person didn't want the highlighting the server still went to the work to implement the code highlighting HTML.

As I type this I had an idea though. Why doesn't PerlMonks cache a node after formating all the links and formating? As far as I could tell now it reapplies links and formating everytime the node is displayed. Why not add a feild that is identical to the content but holds the already html formated output? When edits are done it presents the original post, and when submited saves the unformated AND formated copies? This could be a huge bonus even if it saves only microseconds per post. Just thinking out loud so try not to shoot me. Anyway I'm all for CSS based syntax highlighting if it can be in a way that doesn't add huge additional load.

[tye]

Doing this on the server would be too much load (sounds like it'd be way too much load even using existing C code implementations which don't appear to do it in a flexible enough way). And we can't do the highlighting at submit time because people use different code wrapping settings and it'd be a lot to implement caching of the highlighted code (all of that isn't impossible, but it is a whole lot of work).

If you really want it on the server, you should probably buy pair.com a third web server first (we are pushing the current two pretty hard right now).

There is already a client-side implementation. If you want it, use that. If it isn't good enough, improve it.

[gaal]

Not directly answering your question, but here's one way to produce colored syntax:

vim has a convert-to-html (or better: convert-to-xhtml) command that can be used to generate htmlified colorized perl. Here's a shell snippet from the vim docs that with a little love could be a lot of help.

   for f in *.[ch]; do gvim -f +"syn on" +"run! syntax/2html.vim" +"wq" +"q" $f; done

This is pretty slow, so I don't know how happy the site maintainers would be happy about it. Plus, it's going to be a mess figuring out color schemes for this :)

[allolex]

Maybe a Java/ECMAScript-based syntax highlighting method would leave our code unscathed and prevent our server(s) from having to take on the load of doing all the highlighting. Simon Willison's "Syntax highlighting experiment". This has been discussed in this thread (by kutsū) and elsewhere: (Client side) Perl Syntax Highlighter.