appender let you struct convenient append data
go get github.com/tangzixiang/appender
step 1: define a struct and embed appender.Handler
// custom list hand some append method by appender.Handler
type TODOList struct {
appender.Handler
}
type TODO struct {
name string
}step 2: append direct such as slice
list := TODOList{}
list.Append(TODO{"step 1"}, TODO{"step 2"})
fmt.Printf("%+v\n", list.Values())
// Output: [{name:step 1} {name:step 2}]
// or all in one step
fmt.Printf("%+v\n", new(TODOList).Append(TODO{"step 1"}, TODO{"step 2"}).Values())
// Output: [{name:step 1} {name:step 2}]
// or
fmt.Printf("%+v\n", (&TODOList{}).Append(TODO{"step 1"}, TODO{"step 2"}).Values())
// Output: [{name:step 1} {name:step 2}]or append data when you sure
// base list contain "step 1" and "step 2"
list := (&TODOList{}).Append(TODO{"step 1"}, TODO{"step 2"})
// append when you sure
fmt.Printf("%+v\n", list.AppendIf(true)(TODO{"step 3"}).Values())
// Output: [{name:step 1} {name:step 2} {name:step 3}]not use appender mybe write down：
var list []interface{}{TODO{"step 1"}, TODO{"step 2"}}
var verb bool
if(verb){
list = append(list,TODO{"step 3"})
}maybe you can use a callback to decide whether to append use AppendWhen
// when this callback use with AppendWhen below
// sources is [{name:step 1} {name:step 2}]
// appends is [{name:step 3} {name:step 4} {name:step 5}]
// arguments contain a string "step 6"
when := func(sources,appends []interface{}, arguments ...interface{}) bool {
// ensure compStr not in sources or appends item name
// compStr will be "step 6" here
compStr := arguments[0].(string)
for _, d := range sources {
if compStr == d.(TODO).name {
return false
}
}
for _, d := range appends {
if compStr == d.(TODO).name {
return false
}
}
return true
}
// both sources and appends not contain "step 6" so step3/4/5 will append success
list := (&TODOList{}).Append(TODO{"step 1"}, TODO{"step 2"}).
AppendWhen(when, "step 6")(TODO{"step 3"}, TODO{"step 4"}, TODO{"step 5"})
fmt.Printf("%+v\n", list.Values())
// Output: [{name:step 1} {name:step 2} {name:step 3} {name:step 4} {name:step 5}]or use a closure to decide append what
// sources is a empty slice here
// arguments contain a num 2
(&TODOList{}).AppendFrom(func(sources []interface{}, arguments ...interface{}) []interface{} {
length := arguments[0].(int)
ret := make([]interface{}, length)
for i := 0; i < length; i++ {
ret[i] = TODO{fmt.Sprintf("step %v", i+1)}
}
return ret
}, 2)
fmt.Printf("%+v\n", list.Values())
// Output: [{name:step 1} {name:step 2}]MIT © tangzixiang