 | | | Jscript on Linux, a thousand questions | Jscript on Linux, a thousand questions 2004-04-15 - By Bradley Gabe
Back
I've been programming in jscript on linux for the past year and there
are only a handful of caveats to be mindful of when coming from the
windows side:
1- The jscript version (3.0) is older than the windows (5.0+). So you're
missing some functionality on the jscript objects such as string
manipulation and array tools.
These can be easily overcome by extending your jscript object
prototypes, which is documented well enough in the ms online jscript
reference.
Less easily overcome is the lack of error handling in jscript version
3.0, so you're forced to be more careful on how you structure your
script logic. I know I take a lot of special care to check all of my
data and pointers from one block of a script to the next... but
honestly, that's good programming edicate anyway.
2- Backslashes are different. Windows only reads 'em one way, linux can
handle either direction (or is it the opposite... I never remember anymore).
3- File I/O on linux isn't as accessible as windows. So just avoid doing
anything that heavily relies on reading in text files and parsing lines
into strings. You can do it, it's just not as fast and robust as it
could be.
4- Be wary of string characters for newline (\n) and tab (\t) and such
that might differ between linux and windows. Just make sure to test that
they work cross platform before using them.
Everything else is the same... in fact, you can be mostly sure that
anything you build on the linux side will work on windows. This is not
as true the other way around.
To answer some of your questions more directly:
>Is this still the case? if yes, what's the equivalent of
>
>var ch_stuff = new ActiveXObject("XSI.collection") ;
>
>in Jscript on Linux ?
>
The same command works on linux. I use it at least a dozen times a day
while coding.
>What about file I/O? starting a shell command and returning from the shell?
>are these issues easier to address with ActivePython? As I understand, it is
>truly "Active" only in Windows...
>
>
I've run commands through an external shell using the System() call in
XSI. These commands were written in Python, so any functionality you
don't get for file I/O out of jscript or ActivePython within XSI, you
can always build them externally and just call them into your script
that way.
All things considered, I've been treating my switch to the linux version
of jscript as lemonade from lemons. The lack of more complete jscript
objects forced me to learn how to push jscript to the limits and extend
the functionality of the language itself, and I'm certainly better off
for that knowledge now as I use it all over the place, above and beyond
my original intentions.
Also, the lack of error handling has forced me to learn scripting
techniques that are more robust, ways of hooking into objects without
ever risking raising an error. For doing all of that research, I've
developed a much deeper understanding on how to navigate and hook into
the object model and get things done, even in places we're "not supposed
to go" yet.
Best of all, it's turned me into a speed demon. I have an array of
techniques that can walk a script through a scene with 2000 nodes and
filter out any info I need in less than a tenth of a second. That means
I can build interactive tools without having to resort to external SDK
coding... but that's next anyways.
-Brad
--
Bradley R. Gabe
Industrial Light & Magic
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