Table Constructors

Lua Manual Version: 5.1
Table Constructors

Table constructors are expressions that create tables. Every time a constructor is evaluated, a new table is created. A constructor can be used to create an empty table or to create a table and initialize some of its fields. The general syntax for constructors is

	tableconstructor ::= `{´ [fieldlist] `}´
	fieldlist ::= field {fieldsep field} [fieldsep]
	field ::= `[´ exp `]´ `=´ exp | Name `=´ exp | exp
	fieldsep ::= `,´ | `;´

Each field of the form [exp1] = exp2 adds to the new table an entry with key exp1 and value exp2. A field of the form name = exp is equivalent to ["name"] = exp. Finally, fields of the form exp are equivalent to [i] = exp, where i are consecutive numerical integers, starting with 1. Fields in the other formats do not affect this counting. For example,

     a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 }

is equivalent to

       local t = {}
       t[f(1)] = g
       t[1] = "x"         -- 1st exp
       t[2] = "y"         -- 2nd exp
       t.x = 1            -- t["x"] = 1
       t[3] = f(x)        -- 3rd exp
       t[30] = 23
       t[4] = 45          -- 4th exp
       a = t

If the last field in the list has the form exp and the expression is a function call or a vararg expression, then all values returned by this expression enter the list consecutively (see Function Calls). To avoid this, enclose the function call or the vararg expression in parentheses (see Expressions).

The field list can have an optional trailing separator, as a convenience for machine-generated code.

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