README and gomod improved

README.md

@@ -2,6 +2,8 @@
 
 A helper to merge structs and maps in Golang. Useful for configuration default values, avoiding messy if-statements.
 
+Mergo merges same-type structs and maps by setting default values in zero-value fields. Mergo won't merge unexported (private) fields. It will do recursively any exported one. It also won't merge structs inside maps (because they are not addressable using Go reflection).
+
 Also a lovely [comune](http://en.wikipedia.org/wiki/Mergo) (municipality) in the Province of Ancona in the Italian region of Marche.
 
 ## Status
@@ -31,13 +33,15 @@ It is ready for production use. [It is used in several projects by Docker, Googl
 
 ### Important note
 
-Please keep in mind that in [0.3.2](//github.com/imdario/mergo/releases/tag/0.3.2) Mergo changed `Merge()`and `Map()` signatures to support [transformers](#transformers). An optional/variadic argument has been added, so it won't break existing code.
+Please keep in mind that a problematic PR broke [0.3.9](//github.com/imdario/mergo/releases/tag/0.3.9). I reverted it in [0.3.10](//github.com/imdario/mergo/releases/tag/0.3.10), and I consider it stable but not bug-free. Also, this version adds suppot for go modules.
+
+Keep in mind that in [0.3.2](//github.com/imdario/mergo/releases/tag/0.3.2), Mergo changed `Merge()`and `Map()` signatures to support [transformers](#transformers). I added an optional/variadic argument so that it won't break the existing code.
 
-If you were using Mergo **before** April 6th 2015, please check your project works as intended after updating your local copy with ```go get -u github.com/imdario/mergo```. I apologize for any issue caused by its previous behavior and any future bug that Mergo could cause (I hope it won't!) in existing projects after the change (release 0.2.0).
+If you were using Mergo before April 6th, 2015, please check your project works as intended after updating your local copy with ```go get -u github.com/imdario/mergo```. I apologize for any issue caused by its previous behavior and any future bug that Mergo could cause in existing projects after the change (release 0.2.0).
 
 ### Donations
 
-If Mergo is useful to you, consider buying me a coffee, a beer or making a monthly donation so I can keep building great free software. :heart_eyes:
+If Mergo is useful to you, consider buying me a coffee, a beer, or making a monthly donation to allow me to keep building great free software. :heart_eyes:
 
 <a href='https://ko-fi.com/B0B58839' target='_blank'><img height='36' style='border:0px;height:36px;' src='https://az743702.vo.msecnd.net/cdn/kofi1.png?v=0' border='0' alt='Buy Me a Coffee at ko-fi.com' /></a>
 [![Beerpay](https://beerpay.io/imdario/mergo/badge.svg)](https://beerpay.io/imdario/mergo)
@@ -88,7 +92,7 @@ If Mergo is useful to you, consider buying me a coffee, a beer or making a month
 - [bukalapak/snowboard](https://github.com/bukalapak/snowboard)
 - [janoszen/containerssh](https://github.com/janoszen/containerssh)
 
-## Installation
+## Install
 
     go get github.com/imdario/mergo
 
@@ -99,7 +103,7 @@ If Mergo is useful to you, consider buying me a coffee, a beer or making a month
 
 ## Usage
 
-You can only merge same-type structs with exported fields initialized as zero value of their type and same-types maps. Mergo won't merge unexported (private) fields but will do recursively any exported one. It won't merge empty structs value as [they are not considered zero values](https://golang.org/ref/spec#The_zero_value) either. Also maps will be merged recursively except for structs inside maps (because they are not addressable using Go reflection).
+You can only merge same-type structs with exported fields initialized as zero value of their type and same-types maps. Mergo won't merge unexported (private) fields but will do recursively any exported one. It won't merge empty structs value as [they are zero values](https://golang.org/ref/spec#The_zero_value) too. Also, maps will be merged recursively except for structs inside maps (because they are not addressable using Go reflection).
 
 ```go
 if err := mergo.Merge(&dst, src); err != nil {
@@ -125,9 +129,7 @@ if err := mergo.Map(&dst, srcMap); err != nil {
 
 Warning: if you map a struct to map, it won't do it recursively. Don't expect Mergo to map struct members of your struct as `map[string]interface{}`. They will be just assigned as values.
 
-More information and examples in [godoc documentation](http://godoc.org/github.com/imdario/mergo).
-
-### Nice example
+Here is a nice example:
 
 ```go
 package main

doc.go

@@ -4,42 +4,140 @@
 // license that can be found in the LICENSE file.
 
 /*
-Package mergo merges same-type structs and maps by setting default values in zero-value fields.
+A helper to merge structs and maps in Golang. Useful for configuration default values, avoiding messy if-statements.
 
-Mergo won't merge unexported (private) fields but will do recursively any exported one. It also
-won't merge structs inside maps (because they are not addressable using Go reflection).
+Mergo merges same-type structs and maps by setting default values in zero-value fields. Mergo won't merge unexported (private) fields. It will do recursively any exported one. It also won't merge structs inside maps (because they are not addressable using Go reflection).
+
+Status
+
+It is ready for production use. It is used in several projects by Docker, Google, The Linux Foundation, VMWare, Shopify, etc.
+
+Important note
+
+Please keep in mind that a problematic PR broke 0.3.9. We reverted it in 0.3.10. We consider 0.3.10 as stable but not bug-free. . Also, this version adds suppot for go modules.
+
+Keep in mind that in 0.3.2, Mergo changed Merge() and Map() signatures to support transformers. We added an optional/variadic argument so that it won't break the existing code.
+
+If you were using Mergo before April 6th, 2015, please check your project works as intended after updating your local copy with go get -u github.com/imdario/mergo. I apologize for any issue caused by its previous behavior and any future bug that Mergo could cause in existing projects after the change (release 0.2.0).
+
+Install
+
+Do your usual installation procedure:
+
+    go get github.com/imdario/mergo
+
+    // use in your .go code
+    import (
+        "github.com/imdario/mergo"
+    )
 
 Usage
 
-From my own work-in-progress project:
+You can only merge same-type structs with exported fields initialized as zero value of their type and same-types maps. Mergo won't merge unexported (private) fields but will do recursively any exported one. It won't merge empty structs value as they are zero values too. Also, maps will be merged recursively except for structs inside maps (because they are not addressable using Go reflection).
+
+	if err := mergo.Merge(&dst, src); err != nil {
+		// ...
+	}
+
+Also, you can merge overwriting values using the transformer WithOverride.
+
+	if err := mergo.Merge(&dst, src, mergo.WithOverride); err != nil {
+		// ...
+	}
+
+Additionally, you can map a map[string]interface{} to a struct (and otherwise, from struct to map), following the same restrictions as in Merge(). Keys are capitalized to find each corresponding exported field.
+
+	if err := mergo.Map(&dst, srcMap); err != nil {
+		// ...
+	}
+
+Warning: if you map a struct to map, it won't do it recursively. Don't expect Mergo to map struct members of your struct as map[string]interface{}. They will be just assigned as values.
+
+Here is a nice example:
+
+	package main
+
+	import (
+		"fmt"
+		"github.com/imdario/mergo"
+	)
 
-	type networkConfig struct {
-		Protocol string
-		Address string
-		ServerType string `json: "server_type"`
-		Port uint16
+	type Foo struct {
+		A string
+		B int64
 	}
 
-	type FssnConfig struct {
-		Network networkConfig
+	func main() {
+		src := Foo{
+			A: "one",
+			B: 2,
+		}
+		dest := Foo{
+			A: "two",
+		}
+		mergo.Merge(&dest, src)
+		fmt.Println(dest)
+		// Will print
+		// {two 2}
 	}
 
-	var fssnDefault = FssnConfig {
-		networkConfig {
-			"tcp",
-			"127.0.0.1",
-			"http",
-			31560,
-		},
+Transformers
+
+Transformers allow to merge specific types differently than in the default behavior. In other words, now you can customize how some types are merged. For example, time.Time is a struct; it doesn't have zero value but IsZero can return true because it has fields with zero value. How can we merge a non-zero time.Time?
+
+	package main
+
+	import (
+		"fmt"
+		"github.com/imdario/mergo"
+			"reflect"
+			"time"
+	)
+
+	type timeTransformer struct {
 	}
 
-	// Inside a function [...]
+	func (t timeTransformer) Transformer(typ reflect.Type) func(dst, src reflect.Value) error {
+		if typ == reflect.TypeOf(time.Time{}) {
+			return func(dst, src reflect.Value) error {
+				if dst.CanSet() {
+					isZero := dst.MethodByName("IsZero")
+					result := isZero.Call([]reflect.Value{})
+					if result[0].Bool() {
+						dst.Set(src)
+					}
+				}
+				return nil
+			}
+		}
+		return nil
+	}
+
+	type Snapshot struct {
+		Time time.Time
+		// ...
+	}
 
-	if err := mergo.Merge(&config, fssnDefault); err != nil {
-		log.Error(err)
+	func main() {
+		src := Snapshot{time.Now()}
+		dest := Snapshot{}
+		mergo.Merge(&dest, src, mergo.WithTransformers(timeTransformer{}))
+		fmt.Println(dest)
+		// Will print
+		// { 2018-01-12 01:15:00 +0000 UTC m=+0.000000001 }
 	}
 
-	// More code [...]
+Contact me
+
+If I can help you, you have an idea or you are using Mergo in your projects, don't hesitate to drop me a line (or a pull request): https://twitter.com/im_dario
+
+About
+
+Written by Dario Castañé: https://da.rio.hn
+
+License
+
+BSD 3-Clause license, as Go language.
 
 */
 package mergo

go.mod

@@ -1,8 +1,8 @@
-module github.com/aivetech/mergo
+module github.com/imdario/mergo
 
 go 1.13
 
 require (
-	github.com/imdario/mergo v0.3.9 // indirect
+	golang.org/x/tools v0.0.0-20200717024301-6ddee64345a6 // indirect
 	gopkg.in/yaml.v2 v2.3.0
 )

go.sum

@@ -1,5 +1,28 @@
 github.com/imdario/mergo v0.3.9 h1:UauaLniWCFHWd+Jp9oCEkTBj8VO/9DKg3PV3VCNMDIg=
 github.com/imdario/mergo v0.3.9/go.mod h1:2EnlNZ0deacrJVfApfmtdGgDfMuh/nq6Ok1EcJh5FfA=
+github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
+golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200625001655-4c5254603344 h1:vGXIOMxbNfDTk/aXCmfdLgkrSV+Z2tcbze+pEc3v5W4=
+golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20200717024301-6ddee64345a6 h1:nULzSsKgihxFGLnQFv2T7lE5vIhOtg8ZPpJHapEt7o0=
+golang.org/x/tools v0.0.0-20200717024301-6ddee64345a6/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=