Solidity Style Guide

Layout

4 spaces per indentation level

Use spaces for indentation

Use blank lines

contract A {
  // ...
}

contract B {
  // ...
}

Blank lines may be omitted between groups of related one-liners

contract A {
  function spam();
  function ham();
}

Use UTF-8 or ASCII encoding

Place import statements at the top of the file

Functions should be be grouped according to their visibility and ordered:

constructor
fallback function (if exists)
external
public
internal
private

Within a grouping, place the constant functions last.

Use white spaces in expressions

Avoid extraneous whitespaces inthe following situations: immediately inside parenthesis, brackets or braces, with the exception of single line function declaration.

spam(ham[1], Coin({name: "han"})):

// exception

function singleLine() { spam() }

More than one space around an assignment or other operator to align with

1
2
3

x = 1;
y = 2;
long_variable = 3;

Don’t include a whitespace in the fallback function

function() {
  // ...
}
// not 
function () {
  // ...
}

For control structure whose body contains a single statement, omitting the braces is ok if the statement is contained on a single line

if (x < 10)
    x += 1;
else
    x -= 1;

Function declaration

function increment(uint x) returns (uint) {
    return x + 1;
}
// visibility precedes custom modifier
function increment(uint x) public onlyOwner returns (uint) {
    return x + 1;
}
// long parameters list
function increment(
    uint x1,
    uint x2,
    uint x3,
    uint x4,
    uint x5,
    uint x6,
) {
  // ...
}
// long visibility modifier list
function increment (uint x)
    public
    onlyOwner
    priced
{
    // ...
}