[PROPOSAL] [PATCH] simple method call

[Rodrigo Azevedo <rodrigoams@...>]

REASONING

There are uncountable examples of "methods" that do not need an argument, for example

led[1]:blink

arm[2].pos[3]:go

z:abs

z:Re

polynomial:diff

etc

PROPOSAL

Raise the "methods" syntactic sugar ":" to a function call without arguments, with the exception of the ubiquitous "self", namely, call "methods" without the common usage of  '(' ')', or '{' '}' or ' " ' ' " '.

PATCH

This patch applies a minimalist update of lparser.c to implement the described behaviour.

For Lua 5.3.0

EXAMPLE USAGE

unpack, istable = table.unpack, function(t) return type(t) == 'table' end

t = {}
t.name = "testing ... "
function t:prt (str) print(self.name .. ((istable(str) and str[1]) or str or "") .. " OK") end

t:prt -- NEW!

t:prt ()
t:prt "string"
t:prt {"table"}

t:prt
("ambiguity")

t:prt
(print("OI"))

print("c'est fini")

--

Rodrigo Azevedo Moreira da Silva

--- lparser.c	2015-06-11 08:34:36.553415456 -0300
+++ lparser.c	2015-06-11 08:18:07.138728628 -0300
@@ -808,7 +808,7 @@
 }
 
 
-static void funcargs (LexState *ls, expdesc *f, int line) {
+static void funcargs (LexState *ls, expdesc *f, int line, int is_method) {
   FuncState *fs = ls->fs;
   expdesc args;
   int base, nparams;
@@ -834,7 +834,11 @@
       break;
     }
     default: {
-      luaX_syntaxerror(ls, "function arguments expected");
+      if (is_method) { /* funcargs -> '(' ')' */
+          args.k = VVOID;
+      } else {
+        luaX_syntaxerror(ls, "function arguments expected");
+      }
     }
   }
   lua_assert(f->k == VNONRELOC);
@@ -908,12 +912,12 @@
         luaX_next(ls);
         checkname(ls, &key);
         luaK_self(fs, v, &key);
-        funcargs(ls, v, line);
+        funcargs(ls, v, line, 1);
         break;
       }
       case '(': case TK_STRING: case '{': {  /* funcargs */
         luaK_exp2nextreg(fs, v);
-        funcargs(ls, v, line);
+        funcargs(ls, v, line, 0);
         break;
       }
       default: return;