README.md
1# hashstructure [![GoDoc](https://godoc.org/github.com/mitchellh/hashstructure?status.svg)](https://godoc.org/github.com/mitchellh/hashstructure)
2
3hashstructure is a Go library for creating a unique hash value
4for arbitrary values in Go.
5
6This can be used to key values in a hash (for use in a map, set, etc.)
7that are complex. The most common use case is comparing two values without
8sending data across the network, caching values locally (de-dup), and so on.
9
10## Features
11
12 * Hash any arbitrary Go value, including complex types.
13
14 * Tag a struct field to ignore it and not affect the hash value.
15
16 * Tag a slice type struct field to treat it as a set where ordering
17 doesn't affect the hash code but the field itself is still taken into
18 account to create the hash value.
19
20 * Optionally, specify a custom hash function to optimize for speed, collision
21 avoidance for your data set, etc.
22
23 * Optionally, hash the output of `.String()` on structs that implement fmt.Stringer,
24 allowing effective hashing of time.Time
25
26 * Optionally, override the hashing process by implementing `Hashable`.
27
28## Installation
29
30Standard `go get`:
31
32```
33$ go get github.com/mitchellh/hashstructure
34```
35
36## Usage & Example
37
38For usage and examples see the [Godoc](http://godoc.org/github.com/mitchellh/hashstructure).
39
40A quick code example is shown below:
41
42```go
43type ComplexStruct struct {
44 Name string
45 Age uint
46 Metadata map[string]interface{}
47}
48
49v := ComplexStruct{
50 Name: "mitchellh",
51 Age: 64,
52 Metadata: map[string]interface{}{
53 "car": true,
54 "location": "California",
55 "siblings": []string{"Bob", "John"},
56 },
57}
58
59hash, err := hashstructure.Hash(v, nil)
60if err != nil {
61 panic(err)
62}
63
64fmt.Printf("%d", hash)
65// Output:
66// 2307517237273902113
67```
68