github.com/clem109/go-ethereum@v1.8.3-0.20180316121352-fe6cf00f480a/common/hexutil/json_example_test.go (about)

     1  // Copyright 2017 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package hexutil_test
    18  
    19  import (
    20  	"encoding/json"
    21  	"fmt"
    22  
    23  	"github.com/ethereum/go-ethereum/common/hexutil"
    24  )
    25  
    26  type MyType [5]byte
    27  
    28  func (v *MyType) UnmarshalText(input []byte) error {
    29  	return hexutil.UnmarshalFixedText("MyType", input, v[:])
    30  }
    31  
    32  func (v MyType) String() string {
    33  	return hexutil.Bytes(v[:]).String()
    34  }
    35  
    36  func ExampleUnmarshalFixedText() {
    37  	var v1, v2 MyType
    38  	fmt.Println("v1 error:", json.Unmarshal([]byte(`"0x01"`), &v1))
    39  	fmt.Println("v2 error:", json.Unmarshal([]byte(`"0x0101010101"`), &v2))
    40  	fmt.Println("v2:", v2)
    41  	// Output:
    42  	// v1 error: hex string has length 2, want 10 for MyType
    43  	// v2 error: <nil>
    44  	// v2: 0x0101010101
    45  }