How to use stacks from LC 5.5.3 with LC 4.5.3?

[Richard Gaskin]

Alejandro Tejada wrote:

> Hi All,
>
> These bugs... Are in the engine or the IDE?

Unfortunately "not working as they did before" and "having lots of major
probs" don't provide enough detail to understand what problems are 
occurring, and if they're even bugs per se.

There are a few regressions in v5.5.3, but the critical ones have been 
addressed in GM2 so at this point I'm using 5.5.3 for all new work going 
forward, and also migrating most older projects over time.

I've encountered some differences in behavior, but nothing as 
significant as the changes to backgroundBehavior several versions before.

So far most of the differences I've seen relate to htmlText, but as with 
the earlier change to how backgroundBehavior works I would consider 
those differences worthwhile improvements over limitations and 
inconsistencies in earlier versions.

 From time to time as LiveCode evolves, we can expect that there will be 
new features and enhancements to existing features which may require 
some changes to scripts.  Those are very rare; RunRev does an admirable 
job, far beyond Apple and others, in maintaining backward compatibility 
wherever practical, and weigh the impact on existing code in the 
community very carefully before making any decision requiring revision. 
    But sometimes the opportunity for an improvement may require changes 
to our scripts, and thankfully any such changes are called out in bold, 
red type in the Release Notes so we have a chance to consider the impact 
in our work before migrating a project to a new version.

That stacks built with a version using a newer format can't be used in 
earlier versions is not a new issue, or unique to LiveCode.  Ever since 
I started using this engine in '98 I've seen occasional changes to the 
stack file format, and as with any software product it won't be possible 
for a new format to be used by an older version of the app that wasn't 
designed to handle it.

RunRev has gone a step further than MetaCard Corp with that, providing 
an option in the IDE to save in legacy format.  The current IDE includes 
support for the last three formats, so one can go back to engines all 
the way to v2.4 (circa 2002) if they like.

How many other apps have you seen that maintain support for proprietary 
file formats covering a full decade?

To put that in perspective, you can't even run the latest OS X on any 
Mac you purchased from Apple just six years ago.

RunRev goes above and beyond most others with regard to backward 
compatibility.


> Notice that many profesional developers in this platform
> use the MetaCard IDE to create their software.
> So they will never see the "bugs" that you found.

This is rarely the case, limited to differences between the IDEs only, 
since of course the engine that drives the IDE stacks is the same.

That said, that's one of the reasons we maintain the MC IDE, to help 
distinguish between engine and IDE behaviors in those few cases where it 
may not be self-evident.

With RunRev's detailed Release Notes, it is indeed very rarely the case 
that we don't know up front whether a difference we're seeing is caused 
by an engine change or an IDE change.

That is, provided the Release Notes are read. ;)

--
  Richard Gaskin
  Fourth World
  LiveCode training and consulting: http://www.fourthworld.com
  Webzine for LiveCode developers: http://www.LiveCodeJournal.com
  Follow me on Twitter:  http://twitter.com/FourthWorldSys