Implement a TracLinks syntax for targeting line numbers in repository files

[cboos]

In order to support code reviews, either formal or informal, it's necessary to be able to precisely refer to line numbers.

Trac should support a simple syntax for this. I would suggest the following (lifted from ticket #2011):

• source:trunk/README@head or source:trunk/README@123 the new peg revision notation
• source:trunk/README@123#100 the new peg revision notation, with line number (line 100 in revision 123)
• source:trunk/README@123#100:110 line number range support?

While it's obvious what the target of a link to a single line number should be, the target of a range is a little bit less obvious.

[mgood]

Yes, I think this would be generally preferrable to current use of # for specifying a revision. However, I think that we should use the existing line anchors which are like #l100 (though in some ways I'd sort of prefer to change that to #line100, since the lower case 'l' can look a bit like a '1', which is confusing).

Is there any precedence in Trac for deprecating Wiki syntaxes? I think that the current #rev syntax should be removed at some point after the @rev is implemented, but I don't know how we'd want to handle that.

[cmlenz]

I don't see how we could support line number ranges, but the rest looks good.

About change #l100 to #line100 I'm not sure that's worth the extra three bytes per line. Maybe just use an upper-case L to avoid it being confused with a 1.

[cmlenz]

Implemented in [2290].

[mgood]

Ok, yeah the uppercase L seems sufficiently clear. However, my main point above was that it seems more consistent to use source:/README@123#L12 so the anchor in the link syntax is the same as the actual URL anchor.

[cmlenz]

Fixed in [2299].