589a5f9aeb
The new version of the urfave/cli library is moving to generics, and it's completely unclear to me why this is an improvement. Their new API is very complicated to understand, which for me, defeats the purpose of golang. In parallel, I needed to do some upcoming cli API refactoring, so this was a good time to look into new libraries. After a review of the landscape, I found the alexflint/go-arg library which has a delightfully elegant API. It does have a few rough edges, but it's otherwise very usable, and I think it would be straightforward to add features and fix issues. Thanks Alex!
132 lines
3.2 KiB
Go
132 lines
3.2 KiB
Go
// Mgmt
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// Copyright (C) 2013-2024+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package empty
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import (
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"fmt"
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"sync"
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"github.com/purpleidea/mgmt/gapi"
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"github.com/purpleidea/mgmt/pgraph"
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)
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const (
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// Name is the name of this frontend.
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Name = "empty"
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)
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func init() {
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gapi.Register(Name, func() gapi.GAPI { return &GAPI{} }) // register
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}
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// Args is the CLI parsing structure and type of the parsed result.
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type Args struct{}
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// GAPI implements the main lang GAPI interface.
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type GAPI struct {
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data *gapi.Data
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initialized bool
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closeChan chan struct{}
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wg *sync.WaitGroup // sync group for tunnel go routines
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}
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// Cli takes an *Info struct, and returns our deploy if activated, and if there
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// are any validation problems, you should return an error. If there is no
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// deploy, then you should return a nil deploy and a nil error.
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func (obj *GAPI) Cli(*gapi.Info) (*gapi.Deploy, error) {
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return &gapi.Deploy{
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Name: Name,
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//Noop: false,
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GAPI: &GAPI{},
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}, nil
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}
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// Init initializes the lang GAPI struct.
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func (obj *GAPI) Init(data *gapi.Data) error {
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if obj.initialized {
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return fmt.Errorf("already initialized")
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}
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obj.data = data // store for later
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obj.closeChan = make(chan struct{})
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obj.wg = &sync.WaitGroup{}
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obj.initialized = true
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return nil
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}
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// Graph returns a current Graph.
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func (obj *GAPI) Graph() (*pgraph.Graph, error) {
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if !obj.initialized {
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return nil, fmt.Errorf("%s: GAPI is not initialized", Name)
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}
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obj.data.Logf("generating empty graph...")
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g, err := pgraph.NewGraph("empty")
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if err != nil {
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return nil, err
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}
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return g, nil
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}
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// Next returns nil errors every time there could be a new graph.
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func (obj *GAPI) Next() chan gapi.Next {
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ch := make(chan gapi.Next)
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obj.wg.Add(1)
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go func() {
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defer obj.wg.Done()
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defer close(ch) // this will run before the obj.wg.Done()
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if !obj.initialized {
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next := gapi.Next{
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Err: fmt.Errorf("%s: GAPI is not initialized", Name),
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Exit: true, // exit, b/c programming error?
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}
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select {
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case ch <- next:
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case <-obj.closeChan:
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}
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return
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}
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// send only one event
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next := gapi.Next{
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Exit: false,
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Err: nil,
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}
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select {
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case ch <- next: // trigger a run (send a msg)
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// pass
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// unblock if we exit while waiting to send!
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case <-obj.closeChan:
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return
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}
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}()
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return ch
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}
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// Close shuts down the lang GAPI.
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func (obj *GAPI) Close() error {
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if !obj.initialized {
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return fmt.Errorf("%s: GAPI is not initialized", Name)
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}
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close(obj.closeChan)
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obj.wg.Wait()
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obj.initialized = false // closed = true
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return nil
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}
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