coding_style.md

Coding Style

When in doubt, use the existing code base to find the proper way to format code or name variables.

Basic rules

The coding style is similar to the one used in Thorin:

• Spaces after control-flow structures (e.g. if (x) and not if(x)),
• Spaces after commas, (x, y), not (x,y),
• Spaces after // and /*,
• Comments start with an uppercase and should be proper English sentences whenever possible,
• Names that are short but expressive if possible. Do:

  bool save_module_before_restart() {
    /* ... */
  }

  Don't:

  // Saves the state of the module before a restart
  bool save() {
    /* ... */
  }

• Braces should not be used if the enclosing block is only one line. Do:

  if (x)
    foo(x);

  Don't:

  if (x) {
    foo(x);
  }

• else should be at the same level as the closing } of the if block, if any.
• Private/protected members (not methods) end with _,
• struct instead of class when most members are public.

In addition, getters/setters should be avoided:

• Use a public member for members with read/write access,
• Use a private member with a public accessor function for read-only members:

class S {
public:
    int foo() const { return foo_; }
private:
    int foo_;
};

Down-casting

Some objects that belong to a class hierarchy that support down-casting (e.g. Types or AST nodes) can be cast with the as or isa methods:

ast::LiteralExpr* lit_expr = ...;
ast::Expr* expr = lit_expr;
ast::LiteralExpr* lit_expr2 = expr->as<ast::LiteralExpr>();

Use as when the expression is known to be of the target type, or isa otherwise (isa returns nullptr when the cast fails). Those two methods use C++'s RTTI internally, and have compile-time checks to make sure that the target class is a sub-class of the current object.

Common Abbreviations

• Expr: Expression
• Ptrn: Pattern
• AST: Abstract Syntax Tree
• Decl: Declaration
• Fn: Function
• Attr: Attribute
• Def: Definition