CODEWITHSUNDEEP
lualua-table
Themud
Themud

Reputation: 58

What is the difference between {} and () in calling a function?

I recently saw a new method, at least to me, for calling functions in Lua and that is by using the curly braces {}, certainly if the parameter was a table. Take this function as an example of what I want to examine:

function test(table)
    for _, i in pairs(table) do
        print(i);
    end
end

test{"What", "is", "the", "difference?"};

In calling the function test(), we used the curly braces "{}" instead of the normal braces "()".

So my questions go, what is the difference between those two? Which is better in performance? When should I use one rather than the other? Why was such a way like this created while the normal braces did the job?

Upvotes: 0

Views: 1579

Answers (1)

Piglet
Piglet

Reputation: 28960

Lua provides two syntactic sugars for function arguments. Their purpose is convenience only.

You may choose whatever you (and your colleagues) prefer in terms of convenience , readability and your software design. Performance-wise there is no difference.

If your only argument is a single literal string or a single new table (table constructor!) you may omit the parenthesis.

From the Lua reference manual:

2.5.8 – Function Calls

Arguments have the following syntax:

args ::= `(´ [explist] `)´
args ::= tableconstructor 
args ::= String

All argument expressions are evaluated before the call. A call of the form f{fields} is syntactic sugar for f({fields}); that is, the argument list is a single new table. A call of the form f'string' (or f"string" or f[[string]]) is syntactic sugar for f('string'); that is, the argument list is a single literal string.

Upvotes: 5

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