Syntax highlighting language hints [duplicate]

Question

Do you think it would be worthwhile to provide hints as to what language to use for the syntax highlighting?

Sometimes I find the highlighting on SQL or VB.NET answers is more distracting than helpful; for example:

• Converting MySQL select to PostgreSQL
• Retrieving data from a VB.NET arraylist of objects

to pick the two I've been looking at recently.

Answer 1

Note that this question is a bit obsolete, because we now infer prettify language type based on the tags.

See more:
Changes to syntax highlighting

This is now implemented. In addition to tag inference, you can manually specify the language as a hint to Google Code Prettify.

The spec is:

<!-- language: lang-or-tag-here -->

    code goes here

<!-- language: lang-or-tag-here -->

    code goes here

You may use either a tag or a prettify language code to specify, though prettify language codes are always guaranteed to work regardless of what language the tag happens to be set to.

Use <!-- language-all: lang-or-tag --> to use the given highlighting for all the following code blocks.

practical examples

For those with little time...

<!-- language: lang-js -->
<!-- language: typescript -->
<!-- language: c# -->

Please note they're all in lower case, even though the language may be uppercase (C#) or mixed case (TypeScript).

Suppress any syntax highlighting (prevents poor, misleading guesses)

<!-- language: lang-none -->

Use language-all and your syntax highlighting choice shall be used for all code blocks that follow:

<!-- language-all: lang-html -->

Available Language Hints Moved

Due to several lists of available hints existing throughout Meta, the entire list has been consolidated and moved to the following FAQ:

What is syntax highlighting and how does it work?

Answer 2

One thing that works now, is to have no highlighting (none being better than wrong) by using <pre> code </pre>.

Answer 3

There are problems with code-prettify,

this [^\s>/] == "example" # is highlighted as a regex, not a comment, 1 / 2

..but it mostly does a really good job

There's no good solution to this, Markdown does not provide a way to specify what language a code-block is (see here), so StackOverflow would need to implement their own way.

In the past I've modified a markdown parser to look for a special first-line, something like..

{{language:python}}
import os
print os.listdir()

The usability problem then is, there's no way to know which languages are supported, or how I should specify say, Visual Basic .NET - should it be visualbasicnet, visual-basic.net, vb.net vbnet, etc..?

I suppose this could be overcome by making the code-block button ask for a language (or maybe add second specific-language-code button), but then the site isn't using Markdown anymore, it's using StackOverflows own non-standard version..

Answer 4

Last I know, the site used a whitelist approach to strip the unsupported tags or unsupported attributes on tags.
So I think it would be easy to at least let us provide the class attribute for the pre tag (right now, it doesn't). That way, we can manually set the language for the syntax highlighting like this :

<pre class="prettyprint lang-sql"><code>
--sql comment here
</code></pre>

To answer the question ; Yes, it would definitely be worthwhile to provide hints as to what language to use for the syntax highlighting. I mean take a look at ask.sqlservercentral.com or ask.sqlteam.com, both of them are stackexchange sites focused on SQL Server. But none of the code examples are highlighted correctly.

Answer 5

A workaround for VB is to add an additional apostrophe ' at the end of every comment line, so that the daft syntax highlighter thinks you've terminated your string.

Dear MarkDown
  'Unterminated 
  Why Is Half My Code Red, It Is Not A String
End Moan

Becomes

Dear MarkDown
  'Terminated '
  This Is How It Should Look
End Moan

I sometimes edit other peoples' posts to add the apostrophes.

---

EDIT based on Joel's suggestion to use ''# which is even better:

Dear MarkDown
  ''# Terminated 
  This Is How It Should Look
End Moan

Answer 6

As I've already said in another answer, this could be helped if the language could be inferred from the tags. That way, this fix would work retroactively, and the work flow wouldn't change.

I know that prettify does have a way to specify the language, it would be only a matter of using that.

Answer 7

Scavenger's answer is a good idea, but # might be something that is valid in the code like a pre-processor command in C++ that can be part of the actual code sample.

I suggest to have something that is specified before the code block in a special way. The code block is indented with 4 spaces, so the language specifier could be indented 3 spaces (and only mean something when appearing immediately before a code block). This follows the simplicity in the markup rules that already exists.

   VB.NET
     Dim myVariable As String 'Here is the first code line
     myVariable = "Hello world"

Answer 8

Adding in an option for very light highlighting that would essentially do little more than colour brackets and isolated literals, treat '' and "" as text delimiters and nothing else would be useful for a vast number of languages currently unsupported.

Functional example code look like crap with the current highlighter as do punctuation-light languages like SQL. Perl is just hilarious.

Actually thinking about it more you wouldn't even want the text stuff. It is too costly a hit to readability when it fails (thinking generic type parameters in F# for example).

Essentially nothing that requires unbounded state and never goes across a new line should function very well. Something that is unbounded but the bounds are highly common like whitespace, new lines, any non-word character, etc. have a high probability of not messing up many languages.

Answer 9

The cleanest syntax I think would be something like this:

# Python:

import this
this.eat()

That is, a language-specific comment mark, space, language identifier on the first line. Of course, "Py", "Python 2.6" and misspellings like "Pyton" should work as well.

Answer 10

Another workaround for VB comments is to include two apostrophes and a pound symbol at the beginning of the line. That way, comments aren't highlighted as text and they stand out better.

''# You're commenting!
Dim c As New Comment()

see this Meta question.

Answer 11

Has anyone seen how terribly this general syntax works for MATLAB? Look at the last piece of code in this question. MATLAB uses apostrophe (') as a matrix transposition operator. As a result, everything in code following it is highlighted as a string in brown.

Comments in MATLAB start with a % and those never get highlighted either. Perhaps we could at least make separate HTML tags for certain languages like <asm></asm> or <matlab></matlab>. This would be very helpful, because posting a non-ugly MATLAB question or answer takes ages of reformatting your original code. I personally volunteer to write the code to implement this, just tell me what to do.