Some syntax troubles

["Alexander Gladysh" <agladysh@...>]

Hi, all!

I'm using Lua 5.0.2.

I'm trying to create a small local DSL for one of my tables in following form:

local Foo =
{
  ["Alpha"] = { op1 "a", op2 "b" };
  ["Beta"] = { op2 "a", op1 "b", op3 "c" };
}

I need to declare opN functions somewhere. As they wouldn't be used in
such context anywhere else, and they should have convenient short and
common names, I want to have their scope as local as possible.

I've tried to put them right into the Foo table:

local Foo =
{
  op1 = function(var) ... end;
  op2 = function(var) ... end;
  op3 = function(var) ... end;

  ["Alpha"] = { op1 "a", op2 "b" };
  ["Beta"] = { op2 "a", op1 "b", op3 "c" };
}

But this 1) reduces readability of declarative code in Foo table, and
2) obviously wouldn't work, since AFAICS at the time when inner tables
ctors are called, outer table members are still not initialized.

What I want can be done by moving opN definitions outside of Foo (as
local functions), and enclosing them along with Foo table constructor
inside some scope:

local MakeFoo = function()
  op1 = function(var) ... end;
  op2 = function(var) ... end;
  op3 = function(var) ... end;

  return
  {
    ["Alpha"] = { op1 "a", op2 "b" };
    ["Beta"] = { op2 "a", op1 "b", op3 "c" };
  }
end

local Foo = MakeFoo();

But this obfuscates the code a bit.

Furthermore, I'd like to write something like:

local my_dsl =
{
  op1 = function(var) ... end;
  op2 = function(var) ... end;
  op3 = function(var) ... end;
};

local Foo = in_context_of(my_dsl)
{
  ["Alpha"] = { op1 "a", op2 "b" };
  ["Beta"] = { op2 "a", op1 "b", op3 "c" };
};

Where 'in_context_of' is some "magic" function, which return functor,
which makes members of my_dsl visible for created table. (Simpler call
would be in_context_of(my_dsl, { ... }).)

However, I do not see how this can be done, since function arguments
are evaluated before function call is done. May be some kind of
'using' declaration construct would help here, but this requires at
least one next release of Lua, and I need solution now. :)

Definitions of opN can be separated from table-constructing function
by passing them as a table parameter:

local my_dsl =
{
  op1 = function(var) ... end;
  op2 = function(var) ... end;
  op3 = function(var) ... end;
};

local Foo = function(c)
  return
  {
    ["Alpha"] = { c.op1 "a", c.op2 "b" };
    ["Beta"] = { c.op2 "a", c.op1 "b", c.op3 "c" };
  }
end(my_dsl);

Looks weird though. I'd say, that some macroses would help to hide
weird prologue and epilogue, and some 'with'-like construct would help
to remove that ugly 'c.' prefix. But Lua does not have neither
construct.

Any suggestions?

Thanks in advance,
Alexander.