default values for CGI substitutions

[tbonfort]

I very often use url overloading with the %key% syntax in my mapfile as I find it's a powerful means of building custom maps. The problem with the current implementation is that the mapfile more often than less becomes unparsable if the url doesn't contain the key=value parameter.

Would it be complicated to modify the parser so that the mapfile can contain a default value for %key%, that would be applied if the url does not contain the "key" parameter?

[tbonfort]

looking at the code, it seems like we could loop through metadata %key%_default_value entries to replace the value after having processed the url key/values, thus populating the strings with a default value if the entry was not found in the url.

does this seem reasonable? if so I can take this, unless if Steve wants to keep the hand on that part of the code.

Yeah, that would work, great suggestion. Feel free to add. I'd rather have multiple people work on code sections anyway. More eyes the better!

[tbonfort]

committed in r9279, off to docs

[tbonfort]

doc updated in r9280

[tamas]

Fixed msApplyDefaultSubstitutions causing the process to hang in an infinite loop in r9282