The Fortress Language Specification - CiteSeerX

9.2 Method Declarations
Syntax:
MdDecl ::= AbsMdDecl
| MdDef
AbsMdDecl ::= [abstract ] MdMod ∗ MdHeader
MdDef ::= MdMod ∗ MdHeader = Expr
| Coercion
MdMod ::= getter | setter | FnMod
MdHeader ::= [(Id | self ) . ]Id [StaticParams]([MdParams])[IsType] FnClauses
MdParams ::= MdParam( , MdParam) ∗
| [MdParam( , MdParam) ∗ , ] Id : TypeRef ...
| [MdParam( , MdParam) ∗ , ] [Id : TypeRef ... , ] MdParam=Expr ( , MdParam=Expr) ∗
MdParam ::= ParamId [IsType]
| self
| TypeRef
ParamId ::= Id
|
IsType ::= : TypeRef
FnClauses ::= [Throws] [Where] [Contract]
Throws ::= throws MayTraitTypes
A trait declaration contains a set of method declarations. Syntactically, a method declaration begins with an optional
sequence of modifiers followed by the method’s name optionally prefixed by a self parameter, optional static parameters
(described in Chapter 11), the value parameter with its (optionally) declared type, an optional type of a return
value, an optional declaration of thrown checked exceptions (discussed in Chapter 14), an optional where clause (discussed
in Section 11.6), an optional contract for the method (discussed in Section 9.4), and finally an optional body
expression preceded by the token = . A throws clause does not include naked type variables. Every element in a
throws clause is a subtype of CheckedException. A trait declaration may contain coercions discussed in Chapter 17.
Method declarations can include the following special modifiers:
getter : A method declaration with the modifier getter explicitly declares a getter method for a field, even in the
absence of an actual field. If such a field exists, there is no implicit getter for the field. An explicitly declared getter
method must take no arguments and return an appropriately typed result. A getter method must not throw any checked
exception. Getter names may not overlap ordinary method names. A getter method must be invoked with the field
access syntax:
expr.id
where id is the name of the getter method.
setter : A method declaration with the modifier setter explicitly declares a setter method for a field, even in
the absence of an actual field. If such a field exists, there is no implicit setter for the field. An explicitly declared
setter method must take a single argument—the value being set—and return () . A setter method must not throw any
checked exception. Setter names may not overlap ordinary method names. A setter method must be invoked with the
assignment syntax:
expr 1 .id := expr 2
We say that a method declaration occurs in a trait declaration. A trait declaration declares a method declaration that
occurs in that trait declaration. A trait declaration inherits method declarations from the declarations of its supertraits.
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