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Am 25.04.2013 01:32 schröbte Jay Carlson:


local a=7
local a

In this example it doesn't matter whether you paste this at the REPL or not. :-)

It does if you have a non-nil global "a".


I don't have any suggestions. But writing your code in localized style implies you either won't be *interacting* with it, or that you have a more sophisticated IDE than just an xterm.

My suggestion would be to make a proper interactive interpreter that respects the local environment. I have some ideas, but it is late, so maybe they are utter nonsense ...:

Assuming we have a valid chunk that can be compiled via load(string). If we have identified the locals in the previous chunk using something like lbci[*] we can do some source code transformation on the current chunk to add those locals at the beginning. Problem is, we need a way to save the locals at the end of a chunk, and we need to handle upvalues. I think we can solve both problems in one go:

We append something like "\n; return function() return a, b, c end", where `a`, `b`, `c` are the locals, to the end of the chunk, and get a function which we can query for the upvalue ids.

To load the next chunk `chunk2` we need to run something like

    return function( a, b, c )
      return function()
        ; return function() return a, b, c, d, e end

to get a function that is equivalent to `chunk2` but uses upvalues for the locals `a`, `b`, and `c`. Now we can use debug.upvalueid and debug.upvaluejoin, to merge the upvalues of the function returned from the last chunk and this one.
And if that works, we can _finally_ get rid of "global by default" :-p ...

What do you think? Did I miss something?


Good night,

  [*]:  What is the status of lbci for Lua 5.2 by the way?