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package netlink_test
import (
"fmt"
"log"
"github.com/mdlayher/netlink"
)
// encodeNested is a nested structure within out.
type encodeNested struct {
A, B uint32
}
// encodeOut is an example structure we will use to pack netlink attributes.
type encodeOut struct {
Number uint16
String string
Nested encodeNested
}
// encode is an example function used to adapt the ae.Nested method
// to encode an arbitrary structure.
func (n encodeNested) encode(ae *netlink.AttributeEncoder) error {
// Encode the fields of the nested structure.
ae.Uint32(1, n.A)
ae.Uint32(2, n.B)
return nil
}
func ExampleAttributeEncoder_encode() {
// Create a netlink.AttributeEncoder that encodes to the same message
// as that decoded by the netlink.AttributeDecoder example.
ae := netlink.NewAttributeEncoder()
o := encodeOut{
Number: 1,
String: "hello world",
Nested: encodeNested{
A: 2,
B: 3,
},
}
// Encode the Number attribute as a uint16.
ae.Uint16(1, o.Number)
// Encode the String attribute as a string.
ae.String(2, o.String)
// Nested is a nested structure, so we will use the encodeNested type's
// encode method with ae.Nested to encode it in a concise way.
ae.Nested(3, o.Nested.encode)
// Any errors encountered during encoding (including any errors from
// encoding nested attributes) will be returned here.
b, err := ae.Encode()
if err != nil {
log.Fatalf("failed to encode attributes: %v", err)
}
// Now decode the attributes again to verify the contents.
ad, err := netlink.NewAttributeDecoder(b)
if err != nil {
log.Fatalf("failed to decode attributes: %v", err)
}
// Walk the attributes and print each out.
for ad.Next() {
switch ad.Type() {
case 1:
fmt.Println("uint16:", ad.Uint16())
case 2:
fmt.Println("string:", ad.String())
case 3:
fmt.Println("nested:")
// Nested attributes use their own nested decoder.
ad.Nested(func(nad *netlink.AttributeDecoder) error {
for nad.Next() {
switch nad.Type() {
case 1:
fmt.Println(" - A:", nad.Uint32())
case 2:
fmt.Println(" - B:", nad.Uint32())
}
}
return nil
})
}
}
// Output: uint16: 1
// string: hello world
// nested:
// - A: 2
// - B: 3
}
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