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coding-stylegocurly-braces

Why does Golang enforce curly bracket to not be on the next line?

correct:

if(true) {

}

incorrect:

if(true)
{

}

Why is this style enforced, does it have something to do with the language spec, or is it just because they prefer one style over another ?

Solution

  • Most C descended languages use the style if ( <condition> ) <statement>, the statement is executed if condition is true. The statement can be either a single statement or brace enclosed block.

    Go's if statements require a following brace enclosed block, not a single statement. This is to head off a common error that most style guides try to avoid by requiring that all if statements use braces.

    //subtle error in C
if (<condition>)
  <statement1>;
  <statement2>;

    Now that Go requires a brace block following the if statement the () are redundant. They only serve to help the lexer differentiate between the condition and the statement, otherwise if <condition> <statement> is hard to parse. (Where does the condition end and the statement begin?)

    Now Go's authors have a decision to make:

    • Keep the redundant ()
    • require { to follow the <condition>

    They decided redundancy was not desirable. This had a second side effect. Since there is an implicit ; at every newline, if the { is on the following line a ; gets put between the <condition> and the {. Go's authors again are faced with a decision:

    • special case the parser to be smart about the <condition>; { construct
    • require everyone adopt a common style of if ... { on the same line.
    • require that the <condition> be on a single line.

    Special casing the parser is a very bad thing. Look at the speed D and Go parsers compared to C++'s terrible parser performance. Also a uniform style is a good thing. Their ultimate decision is pretty simple given the constraints.