C preprocessor style #line support

[Joshua Jensen <josh.jjensen@...>]

I was reading through the archives to determine what became of the 
recent #line mention in the "goto" conversation, but I didn't see anything.

I'm porting scripts from an in-house scripting language to Lua.  The 
in-house scripting language uses a lot of C-style #includes and #defines 
for values.  Originally, I thought the use of the preprocessor was 
silly, but as I've ported more and more scripts, I've come to realize 
there are some good uses of #define in there.

So I started thinking about how to coax Lua into doing this _and_ allow 
a Lua debugger to still work.

In fileA.lua, we could have:

local MY_DEFINE = 5  -- Equivalent of #define MY_DEFINE 5
local YOUR_DEFINE = 10  -- Equivalent of #define YOUR_DEFINE 10

In fileB.lua, we would use them:

print(MY_DEFINE)
print(YOUR_DEFINE)

This doesn't work of course.

If I concatenate the two files together manually, it would only work for 
execution, not for debugging.

It would be nice to feed this to Lua (or equivalent):

#line 1 "fileA.lua"
local MY_DEFINE = 5
#line 2 "fileA.lua"
local YOUR_DEFINE = 10
#line 1 "fileB.lua"
print(MY_DEFINE)
#line 2 "fileB.lua"

In this case, the debugger could properly step between files, because 
Lua would return the proper script filename.  In fact, there are all 
kinds of spiffy tricks that could be done with #line.

Are there any fancy techniques to pull this off?  Noticing the layout of 
the Proto structure, I don't think there are.  It seems to have only one 
filename per Proto.

Thanks!

Josh