golang-default

Initialize or New Struct with default value

Setup

go get github.com/rebirthlee/golang-default

Support type

• int/8/16/32/64, uint/8/16/32/64

`def:"100"` 
`def:"-100"` // support only signed integer
// support hexadecimal, octal, binary
`def:"0xff"` // hexadecimal
`def:"0xFF"` // hexadecimal
`def:"0o77"` // octal
`def:"0b11001111"` // binary

• float32/64

`def:"3.141592653589"`
`def:"-3.141592"`

• complex64/128

 // `def:"{real part},{imaginary part}"`
`def:"3.14,-10"`
`def:"-3.14,3"`

• time.Duration

// calling time.ParseDuration
`def:"1h"` // 1 * time.Hour

• time.Time

`def:"now"` // time.Now()
`def:"+1h"` // time.Now().Add(1 * time.Hour)
`def:"-1h"` // time.Now().Add(-1 * time.Hour)

• Nested Struct

type Parent struct {
	Name string `def:"Parent Struct"`
	OneChild Child `def:"dive"`
	TwoChild Child `def:"dive"`
}

type Child struct {
	Key string `def:"unknown"`
	Number int `def:"-1"`
}

• Pointer of type

type Parent struct {
	Name *string `def:"Parent Struct"`
	OneChild *Child `def:"dive"`
	TwoChild *Child `def:"dive"`
}

type Child struct {
	Key *string `def:"unknown"`
	Number *int `def:"-1"`
}

• Array

type Sample struct {
	Arr [3]int `def:"dive,-1"` // [-1, -1, -1]
}

• Slice

type Sample struct {
	// `def:"dive({length},{capacity(optional)}),{value}"`
	Sli []int `def:"dive(5),-1"` // [-1, -1, -1, -1, -1]
  
	//cap(SliWithCap) == 7
	SliWithCap []NestedSample `def:"dive(3,7),dive"` // [{nested struct},{nested struct},{nested struct}] 
}

type NestedSample struct {
	Name string `def:"nested struct"`
}

• Map

type Sample struct {
	DiveMap map[string]*Struct `def:"dive{\"john doe\":dive,\"some one\":dive,\"key\":dive}"`
/*
	{ 
		"john doe": &{who?},
		"some one": &{who?},
		"key": &{who?}
	}
*/ 
	StructKeyMap map[*Struct]bool `def:"dive{dive:true,dive:false,dive:true}"`
/*
	{ 
		&{who?}: true,
		&{who?}: false,
		&{who?}: true
	}
*/
	DiveNestedMap map[string]map[*Struct]bool `def:"dive{\"key1\":dive{dive:true,dive:false},\"key2\":dive{dive:false,dive:false}}"`
/*
	{ 
		"key1": {
			&{who?}: true,
			&{who?}: false
		},
		"key2": {
			&{who?}: false,
			&{who?}: false
		}
	}
*/
}

Struct struct {
	Name string `def:"who?"`
}

• Json

type Sample struct {
	Arr [3]int `def:"[1,2,3]"` // [1,2,3] 
	Sli []string `def:"[\"slice 1\",\"slice 2\"]"` // [slice 1,slice 2]
	Map map[string]interface{} `def:"{\"key1\":123,\"key2\":\"value\",\"nested map\":{\"key\":\"val\"}}"` 
/*
	{ 
		"key1":123,
		"key2":"value",
		"nested map":{
			"key":"val"
		}
	}
*/

	Nested NestedSample `def:"{\"displayName\":\"nested struct type\"}"` // {nested struct type}
	PtrNested *NestedSample `def:"{\"displayName\":\"nested struct pointer type\"}"` // &{nested struct pointer type}
}

type NestedSample struct {
	Name string `json:"displayName"`
}

• Function

Example

Usage

Simple

import (
	"fmt"
	"github.com/rebirthlee/golang-default"
)

type Person struct {
	Age int `def:"20"`
	Name string `def:"hellp"`
}

...
var p Person
if err := def.Init(&p); err != nil {
	// error handle
}
fmt.Println(p) //out: {20 hellp}

Init

If you got error, the next field of struct will not be initialized.

if err := def.Init(&p); err != nil {
	// error handle
}

JustInit

Even though it has an error, It will try to initialize all fields. And you can know that error field of struct.

if err := def.JustInit(&p); err != nil {
	justErr := err.(*def.ErrorJustInit)
	fmt.Println(justErr.Error())
	// error handle
}

MustInit

It isn't return error. but it will be panic when you has an error.

def.MustInit(&p) // hasn't return error.

New

If you got error, it will be return nil.

i, err := def.New(Person{})
if err != nil {
	// error handle
} else {
  p := i.(*Person)
  fmt.Println(p) //out: &{20 hellp}
}

JustNew

Even though it has an error, It must return pointer of struct with error.

i, err := def.JustNew(Person{})
if err != nil {
	justErr := err.(*def.ErrorJustInit)
	fmt.Println(justErr.Error())
	// error handle
} 
p := i.(*Person)
fmt.Println(p) //out: &{20 hellp}

MustNew

It isn't return error. but it will be panic when you has an error.

p := def.MustNew(Person{}).(*Person) // hasn't return error.
fmt.Println(p) //out: &{20 hellp}

License

THE BEER-WARE LICENSE (Revision 42)