"LiveCode Infinity": lexically-scoped variables and bytecode blocks
Peter TB Brett
peter.brett at livecode.com
Tue Jun 7 07:05:44 EDT 2016
Just a quick update to let you know that work has already started on the
"LiveCode Infinity" improvements to LiveCode Builder.
There are two really interesting things that will be finished soon.
Variables in LCB are going to become lexically scoped
(https://github.com/livecode/livecode/pull/4113). This means that
variables declared inside an "if" or "repeat" block won't be accessible
after the end of that block.
if true then
variable tVar as String
-- tVar isn't accessible here
This also means that if you have a "repeat" loop, the variables that are
declared inside the loop will be automatically reset on each iteration.
It helps avoid bugs where temporary values created inside a loop get
carried over to the next run of the loop.
repeat 5 times
variable tVar as optional String
-- tVar is reset to "nothing" every time the loop runs
If you wanted tVar to be preserved from one iteration to the next, you
can simply move the declaration outside the "repeat" loop.
Finally, it means that you can now "shadow" variables. For example,
this will become valid LCB code:
variable tX as Array
repeat 5 times
variable tX as Number
repeat 4 times
variable tX as String
The second new feature is the "bytecode" block
(https://github.com/livecode/livecode/pull/4097). This lets you write
blocks of raw LCB bytecode in your LCB source files. At the moment
there are not very many places where this is likely to be useful, but in
the future when we add more bytecodes (as part of the "LiveCode
Infinity" project) bytecode blocks will let us write much more of LCB in
I believe that "unsafe" blocks and "unsafe" handlers will be added soon.
These will be used to mark code that does risky direct memory
Dr Peter Brett <peter.brett at livecode.com>
LiveCode Technical Project Manager
LiveCode 2016 Conference: https://livecode.com/edinburgh-2016/
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