qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-11-22 13:14:55 -07:00
Code Releases Activity

handle the nil interface better in reflect and print

Browse Source 
R=rsc
DELTA=25  (19 added, 0 deleted, 6 changed)
OCL=20985
CL=20985
This commit is contained in:
Rob Pike 2008-12-11 12:59:49 -08:00
parent 793a6effcf
commit ac09eb4f49
3 changed files with 25 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/lib/fmt/print.go
View File

@ -307,10 +307,13 @@ func parsenum(s string, start, end int) (n int, got bool, newi int) {
}
func (p *P) printField(field reflect.Value) (was_string bool) {
if stringer, ok := field.Interface().(String); ok {
inter := field.Interface();
if inter != nil {
if stringer, ok := inter.(String); ok {
p.addstr(stringer.String());
return false; // this value is not a string
}
}
s := "";
switch field.Kind() {
case reflect.BoolKind:
@ -363,6 +366,14 @@ func (p *P) printField(field reflect.Value) (was_string bool) {
p.add('{');
p.doprint(field, true, false);
p.add('}');
case reflect.InterfaceKind:
inter := field.(reflect.InterfaceValue).Get();
if inter == nil {
s = "<nil>"
} else {
// should never happen since a non-nil interface always has a type
s = "<non-nil interface>";
}
default:
s = "?" + field.Type().String() + "?";
}
@ -421,8 +432,9 @@ func (p *P) doprintf(format string, v reflect.StructValue) {
}
field := getField(v, fieldnum);
fieldnum++;
if c != 'T' { // don't want thing to describe itself if we're asking for its type
if formatter, ok := field.Interface().(Format); ok {
inter := field.Interface();
if inter != nil && c != 'T' { // don't want thing to describe itself if we're asking for its type
if formatter, ok := inter.(Format); ok {
formatter.Format(p, c);
continue;
}

6
src/lib/reflect/type.go
View File

@ -340,6 +340,8 @@ func (t *InterfaceTypeStruct) Len() int {
return len(t.field)
}
var NilInterface = NewInterfaceTypeStruct("nil", "", new([]Field, 0));
// -- Func
export type FuncType interface {
@ -834,6 +836,10 @@ func (p *Parser) Type(name string) *StubType {
}
export func ParseTypeString(name, typestring string) Type {
if typestring == "" {
// If the typestring is empty, it represents (the type of) a nil interface value
return NilInterface
}
p := new(Parser);
p.str = typestring;
p.Next();

3
src/lib/reflect/value.go
View File

@ -59,6 +59,7 @@ type Creator *(typ Type, addr Addr) Value
export type MissingValue interface {
Kind() int;
Type() Type;
Addr() Addr;
}
type MissingValueStruct struct {
@ -66,7 +67,7 @@ type MissingValueStruct struct {
}
func MissingCreator(typ Type, addr Addr) Value {
return &MissingValueStruct{ Common{IntKind, typ, addr} }
return &MissingValueStruct{ Common{MissingKind, typ, addr} }
}
// -- Int