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/*
* Copyright (C) 2014 ~ 2018 Deepin Technology Co., Ltd.
*
* Author: jouyouyun <jouyouwen717@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package initializer
// TODO:
// 1. a Promise like initializer might be better.
// 2. using reflect to support different initializer.
// Initializer is a chainable initializer. Init/InitOnSystemBus/InitOnSystemBus will accept a initializer,
// and then pass the successful return value to the next initializer. If error occurs, the rest initializers
// won't be executed any more. GetError is used to access the error.
type Initializer struct {
v interface{}
e error
}
// NewInitializer creates a new Initializer.
func NewInitializer() *Initializer {
return new(Initializer)
}
func noop(v interface{}) (interface{}, error) {
return v, nil
}
func (i *Initializer) initWithHandler(fn func(interface{}) (interface{}, error), handler func(interface{}) (interface{}, error)) *Initializer {
if i.e != nil {
return i
}
var err error
var v interface{}
v, err = fn(i.v)
if err != nil {
i.e = err
return i
}
v, err = handler(v)
if err != nil {
i.e = err
}
i.v = v
return i
}
// Init accepts a initializer function, and pass the successful return value to next initializer.
func (i *Initializer) Init(fn func(interface{}) (interface{}, error)) *Initializer {
return i.initWithHandler(fn, noop)
}
// GetError returns the first error of initializers.
func (i *Initializer) GetError() error {
return i.e
}
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