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Adds Persistent{Pre,Post}Run hook chaining #1253

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2 changes: 1 addition & 1 deletion .golangci.yml
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ linters:
- ineffassign
- interfacer
#- lll
- maligned
# - maligned
- megacheck
#- misspell
#- nakedret
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165 changes: 130 additions & 35 deletions command.go
Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,21 @@ type Command struct {
// * PersistentPostRun()
// All functions get the same args, the arguments after the command name.
//
// When TraverseChildrenHooks is set, PersistentPreRun and
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Maybe worth adding something like By default, if PersistentPreRun or PersistentPostRun is set, the parent's Pre/Post run hooks are not executed?

// PersistentPostRun are chained together so that each child
// PersistentPreRun is ran, and the PersistentPostRun are ran in reverse
// order. For example:
//
// Commands: root -> subcommand-a -> subcommand-b
//
// root - PersistentPreRun
// subcommand-a - PersistentPreRun
// subcommand-b - PersistentPreRun
// subcommand-b - Run
// subcommand-b - PersistentPostRun
// subcommand-a - PersistentPostRun
// root - PersistentPostRun
//
// PersistentPreRun: children of this command will inherit and execute.
PersistentPreRun func(cmd *Command, args []string)
// PersistentPreRunE: PersistentPreRun but returns an error.
Expand Down Expand Up @@ -193,6 +208,11 @@ type Command struct {
// TraverseChildren parses flags on all parents before executing child command.
TraverseChildren bool

// TraverseChildrenHooks will have each subcommand's PersistentPreRun and
// PersistentPostRun instead of overriding. It should be set on the root
// command.
TraverseChildrenHooks bool
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I think it's worth adding some checks to ensure that this is set in the root command only (because traverseChildrenHooks cares only about root command).


// Hidden defines, if this command is hidden and should NOT show up in the list of available commands.
Hidden bool

Expand Down Expand Up @@ -829,55 +849,130 @@ func (c *Command) execute(a []string) (err error) {
return err
}

for p := c; p != nil; p = p.Parent() {
if p.PersistentPreRunE != nil {
if err := p.PersistentPreRunE(c, argWoFlags); err != nil {
return err
// Look to see if TraverseChildrenHooks is set on the root command.
if _, err := c.runTree(c, argWoFlags, c.traverseChildrenHooks()); err != nil {
return err
}

return nil
}

func (c *Command) traverseChildrenHooks() bool {
if c.HasParent() {
return c.Parent().traverseChildrenHooks()
}

return c.TraverseChildrenHooks
}

func (c *Command) runTree(
cmd *Command,
args []string,
traverseChildrenHooks bool,
) (
persistentPostRunEs []func(cmd *Command, args []string) error,
err error,
) {
if c == nil {
return nil, nil
}

// Traverse command tree and save the PersistentPostRun{,E} functions.
persistentPostRunEs, err = c.Parent().runTree(cmd, args, traverseChildrenHooks)
if err != nil {
return nil, err
}

if traverseChildrenHooks || c == cmd {
// PersistentPreRun/PersistentPreRunE
switch {
case c.PersistentPreRun != nil:
c.PersistentPreRun(cmd, args)
case c.PersistentPreRunE != nil:
if err := c.PersistentPreRunE(cmd, args); err != nil {
return nil, err
}
break
} else if p.PersistentPreRun != nil {
p.PersistentPreRun(c, argWoFlags)
break
default:
// Doesn't have a registered PersistentPreRun{,E}. Move on...
}

// PersistentPostRun/PersistentPostRunE
switch {
case c.PersistentPostRun != nil:
persistentPostRunEs = append(
persistentPostRunEs,
func(cmd *Command, args []string) error {
c.PersistentPostRun(cmd, args)
return nil
},
)
case c.PersistentPostRunE != nil:
persistentPostRunEs = append(
persistentPostRunEs,
c.PersistentPostRunE,
)
default:
// Doesn't have a registered PersistentPostRun{,E}. Move on...
}
}
if c.PreRunE != nil {
if err := c.PreRunE(c, argWoFlags); err != nil {
return err

if c != cmd {
// Don't run a parent command.
return persistentPostRunEs, nil
}

// PreRun/PreRunE
switch {
case c.PreRun != nil:
c.PreRun(cmd, args)
case c.PreRunE != nil:
if err := c.PreRunE(cmd, args); err != nil {
return nil, err
}
} else if c.PreRun != nil {
c.PreRun(c, argWoFlags)
default:
// Doesn't have a registered PreRun{,E}. Move on...
}

if err := c.validateRequiredFlags(); err != nil {
return err
return nil, err
}
if c.RunE != nil {
if err := c.RunE(c, argWoFlags); err != nil {
return err

// Run/RunE
switch {
case c.RunE != nil:
if err := c.RunE(cmd, args); err != nil {
return nil, err
}
} else {
c.Run(c, argWoFlags)
}
if c.PostRunE != nil {
if err := c.PostRunE(c, argWoFlags); err != nil {
return err
case c.Run != nil:
c.Run(cmd, args)
default:
// Both RunE and Run are nil...
panic(fmt.Sprintf("command %q does not have a non-nil RunE or Run function", c.Use))
}

// PostRun/PostRunE
switch {
case c.PostRun != nil:
c.PostRun(cmd, args)
case c.PostRunE != nil:
if err := c.PostRunE(cmd, args); err != nil {
return nil, err
}
} else if c.PostRun != nil {
c.PostRun(c, argWoFlags)
default:
// Doesn't have a registered PostRun{,E}. Move on...
}
for p := c; p != nil; p = p.Parent() {
if p.PersistentPostRunE != nil {
if err := p.PersistentPostRunE(c, argWoFlags); err != nil {
return err
}
break
} else if p.PersistentPostRun != nil {
p.PersistentPostRun(c, argWoFlags)
break

// PersistentPostRun/PersistentPostRunE
// Iterate through the list in reverse order. Similar to a defer, allow
// the topmost commands to cleanup first.
for i := range persistentPostRunEs {
r := persistentPostRunEs[len(persistentPostRunEs)-1-i]
if err := r(cmd, args); err != nil {
return nil, err
}
}

return nil
return nil, nil
}

func (c *Command) preRun() {
Expand Down
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