github.com/vmware/govmomi@v0.43.0/govc/flags/common.go (about)

     1  /*
     2  Copyright (c) 2015-2023 VMware, Inc. All Rights Reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  package flags
    17  
    18  import "sync"
    19  
    20  // Key type for storing flag instances in a context.Context.
    21  type flagKey string
    22  
    23  // Type to help flags out with only registering/processing once.
    24  type common struct {
    25  	register sync.Once
    26  	process  sync.Once
    27  }
    28  
    29  func (c *common) RegisterOnce(fn func()) {
    30  	c.register.Do(fn)
    31  }
    32  
    33  func (c *common) ProcessOnce(fn func() error) (err error) {
    34  	c.process.Do(func() {
    35  		err = fn()
    36  	})
    37  	return err
    38  }