Lua_Extended.txt

For historical purposes only. Do not edit.

Permalink: https://github.com/caligari87/Oblige/blob/e3dbc44e1649e40a65df8da0cc65d13be592fa03/notes/Lua_Extended.txt

LUA EXTENSIONS
==============

The version of Lua used in OBLIGE has been extended to enhance code
readability and to suit my programming style.  Lua 5.1.4 was the
base for this, it had worked well for a long time and the changes
coming in the 5.2 series did not provide anything I wanted.  Hence
I decided to fork the Lua 5.1.4 code into a custom version.


CHANGES
-------

1. Data tables don't require a separator (comma or semicolon) at
   the end of a line to separate the next item.  In the middle of
   a line they are still needed though.  This is analogous to
   statements where semicolons are optional at the end of a line.

   Example:

   x = {
     { 123, 234, 345 }
     { 456, 567, 678 }
     { 789, 891, 912 }
   }


2. Simpler traversal of lists and tables.  I have introduced a new
   keyword 'each' which is similar to 'for' but does not require
   the ipairs() or pairs() functions -- one is called automatically
   (ipairs for a single variable, pairs for two).

   Example (i):  each V in list do ... end

   Example (ii): each K,V in table do ... end

   For list traversal, a local variable called '_index' contains
   the current index value.


3. Continue statement.  This is something I missed a lot from C
   and C++, since I prefer to keep indentation to a minimum and
   to write loops with "filters" near the beginning.

   Example:

      each R in LEVEL.rooms do
        -- ignore outside rooms
        if R.outdoor then continue end

        -- ignore cavey rooms
        if R.kind == "cave" then continue end

        ... do something ...
      end


4. Added != operator with the same meaning as '~=' (not equals)
   since I find it more readable -- the exclamation mark just
   stands out more.


5. Allow string.format '%s' to use __tostring metamethod on a
   non-string argument, especially tables.  It will also convert
   other values to strings, such as "nil" and the booleans.

   This was a power-patch by Doug Currie.