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- corrections and more on interface types

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R=r
DELTA=35  (12 added, 13 deleted, 10 changed)
OCL=16162
CL=16164
This commit is contained in:
Robert Griesemer 2008-09-29 20:37:46 -07:00
parent b6f59358b5
commit a1065faf7c
1 changed files with 20 additions and 21 deletions
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41
doc/go_spec.txt
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@ -36,7 +36,6 @@ Open issues according to gri:
[ ] optional semicolons: too complicated and unclear [ ] optional semicolons: too complicated and unclear
[ ] like to have assert() in the language, w/ option to disable code gen for it [ ] like to have assert() in the language, w/ option to disable code gen for it
[ ] composite types should uniformly create an instance instead of a pointer [ ] composite types should uniformly create an instance instead of a pointer
[ ] meaning of nil
[ ] clarify slice rules [ ] clarify slice rules
[ ] something on tuples? [ ] something on tuples?
[ ] semantics of statements [ ] semantics of statements
@ -62,6 +61,7 @@ Decisions in need of integration into the doc:
for array composites for array composites
Closed issues: Closed issues:
[x] meaning of nil
[x] remove "any" [x] remove "any"
[x] methods for all types [x] methods for all types
[x] should binary <- be at lowest precedence level? when is a send/receive non-blocking? (NO - 9/19/08) [x] should binary <- be at lowest precedence level? when is a send/receive non-blocking? (NO - 9/19/08)
@ -94,13 +94,10 @@ Contents
Export declarations Export declarations
Types Types
Type interfaces
Basic types Basic types
Arithmetic types Arithmetic types
Booleans Booleans
Strings Strings
Array types Array types
Struct types Struct types
Pointer types Pointer types
@ -743,25 +740,26 @@ There are basic types and composite types. Basic types are predeclared.
Composite types are arrays, maps, channels, structures, functions, pointers, Composite types are arrays, maps, channels, structures, functions, pointers,
and interfaces. They are constructed from other (basic or composite) types. and interfaces. They are constructed from other (basic or composite) types.
The 'static type' (or simply 'type') of a variable is the type defined by
the variable's declaration. The 'dynamic type' of a variable is the actual
type of the value stored in a variable at runtime. Except for variables of
interface type, the static and dynamic type of variables is always the same.
Variables of interface type may hold values of different types during
execution. However, the dynamic type of the variable is always compatible
with the static type of the variable.
Type = Type =
TypeName | ArrayType | ChannelType | InterfaceType | TypeName | ArrayType | ChannelType | InterfaceType |
FunctionType | MapType | StructType | PointerType . FunctionType | MapType | StructType | PointerType .
TypeName = QualifiedIdent. TypeName = QualifiedIdent.
The ``interface'' of a type is the set of methods bound to it
(§Method declarations). The interface of a pointer type is the interface
of the pointer base type (§Pointer types). All types have an interface;
if they have no methods associated with them, their interface is
called the ``empty'' interface.
Type interfaces The ``static type'' (or simply ``type'') of a variable is the type defined by
---- the variable's declaration. The ``dynamic type'' of a variable is the actual
type of the value stored in a variable at runtime. Except for variables of
interface type, the dynamic type of a variable is always its static type.
Variables of interface type may hold values with different dynamic types
during execution. However, its dynamic type is always compatible with
the static type of the interface variable (§Interface types).
TODO fill in this section
Basic types Basic types
---- ----
@ -1182,8 +1180,9 @@ Assignment compatibility: A function pointer can be assigned to a function
Interface types Interface types
---- ----
An interface type denotes the set of all types that implement the Type interfaces may be specified explicitly by interface types.
set of methods specified by the interface type. An interface type denotes the set of all types that implement at least
the set of methods specified by the interface type, and the value "nil".
InterfaceType = "interface" "{" [ MethodList [ ";" ] ] "}" . InterfaceType = "interface" "{" [ MethodList [ ";" ] ] "}" .
MethodList = MethodSpec { ";" MethodSpec } . MethodList = MethodSpec { ";" MethodSpec } .
@ -2280,9 +2279,9 @@ A method declaration is a function declaration with a receiver. The receiver
is the first parameter of the method, and the receiver type must be specified is the first parameter of the method, and the receiver type must be specified
as a type name, or as a pointer to a type name. The type specified by the as a type name, or as a pointer to a type name. The type specified by the
type name is called ``receiver base type''. The receiver base type must be a type name is called ``receiver base type''. The receiver base type must be a
type declared in the current file. The method is said to be ``bound'' to type declared in the current file, and it must not be a pointer type.
the receiver base type; specifically it is declared within the scope of The method is said to be ``bound'' to the receiver base type; specifically
that type (§Type interfaces). it is declared within the scope of that type (§Types).
MethodDecl = "func" Receiver identifier FunctionType ( ";" | Block ) . MethodDecl = "func" Receiver identifier FunctionType ( ";" | Block ) .
Receiver = "(" identifier [ "*" ] TypeName ")" . Receiver = "(" identifier [ "*" ] TypeName ")" .