IDE and libUrl

[Dave Cragg]

On 8 Sep 2004, at 03:17, Richard Gaskin wrote:

> Some time ago Dave Cragg wrote:
>
> >> The version of libUrl (1.1a3) currently being distributed with
> >> the Rev 2.5 beta (engine 2.6.1) is not backwards compatible with
> >> earlier engines. This is because of syntax added to support
> >> secure sockets in https URLs.
>
> Can older versions of libURL be used with newer engines (without 
> support for new features, of course)?

Yes.

>
> I'd propose that we do with libURL what we did with the Standalone 
> Builder:  have two versions included in the IDE, and use the version 
> appropriate to the engine being used in that session.
>
> Can anyone think of a downside to that?

>
> For the sake of simplicity I like being able to use one IDE build 
> across all versions of the engine from the time the IDE went open 
> source going forward.  There may be a time when that goal is no longer 
> supportable, but as long as it is I think it's worth doing.
>
> Any downsides to the approach for libURL proposed here?
>
I guess there will be a naming issue with the stack. (start using <???>)

The other issue I'm not so sure about is the potential syntax error 
when using the newer libUrl with an older engine. (The problem syntax 
is "open secure socket ...") I'm not sure exactly when/if the engine 
tries to compile loaded stacks. If compiling is only done when a stack 
is actually called (e.g. after a "start using") then it may be OK. But 
if all substacks in memory are subject to script compilation, then 
there may be a problem. (I guess I could check this out. :))

A thought. (Apologies if this is what you had in mind.) One approach 
might be to make the libUrl stack simply a "loader" stack, with a 
single "libraryStack" handler. The two "functional" versions of libUrl  
would be held in custom properties. The libraryStack handler would 
unpackage the appropriate custom property and start using that stack. I 
just checked if this is feasible, and it seems to be. Although it seems 
you can't use "start using" directly on a custom property, you can "go" 
to a custom property. So something like this might work:

on libraryStack
   if "libUrl_" is not in the stacksInUse then
     if versionLessThan("2.6.1") then
       go invisible stack (the cLibUrl1_0_15 of me) ##contains stack 
"libUrl_1_0_15"
       start using "libUrl_1_0_15"
       close stack  "libUrl_1_0_15"
   else
       go invisible stack (the cLibUrl1_1 of me)
       start using "libUrl_1_1"
       close stack  "libUrl_1_1"
     end if
   end if
end libraryStack

function versionLessThan pTarget
   put the version into tCurV
   set the itemDel to "."
   put 0 into tCount
   repeat for each item tNum in pTarget
     add 1 to tCount
     if item tCount of tCurV < tNum then return true
   end repeat
   return false
end versionLessThan

A problem here might be the size of the libUrl stack that has to be 
carried around, but I guess the custom properties could be compressed.

Too complicated??

By the way, I just noticed that the libUrl pages on the new Rev website 
are incomplete (no links to documentation or downloads). I'll check 
with RunRev what they plan for this. However, it may be a good idea to 
have the latest updaters posted elsewhere. On the Yahoo site perhaps, 
along with the IDE. Or should I put together a separate download site? 
(or both?).

Cheers
Dave