Add OnFinalize method

[yann-soubeyrand]

This method is the OnInitialize counterpart. Like OnInitialize which allows loading the configuration before each command is executed, OnFinalize allows saving the configuration after each command has been executed.

[stmcginnis]

Like OnInitialize which allows loading the configuration before each command is executed, OnFinalize allows saving the configuration after each command has been executed.

Seems like a useful use case to support.

[marckhouzam]

This seems reasonable.
However, I never really understood the use case for initializers.
What is the difference between using an initializer/finalizer compared to a PersistentPreRun/PersistentPostRun?

[jpmcb]

I agree - this seems reasonable, but I think we're looking for a valid use case on this to keep the Cobra API thin: @yann-soubeyrand can you provide a small Cobra CLI program that would require this use case? Thanks much!

[yann-soubeyrand]

This seems reasonable. However, I never really understood the use case for initializers. What is the difference between using an initializer/finalizer compared to a PersistentPreRun/PersistentPostRun?

PersistentPreRun and PersistentPostRun of the root command aren’t run if there are PersistentPreRun and PersistentPostRun in “intermediary commands”. For example, the program here https://github.com/yann-soubeyrand/cobra-test gives the following result:

❯ ./cobra-test parent child
initialize
parent persistent pre run
child called
parent persistent post run
finalize

Also, if using RunE, a PostRun may not be run in case of error:

cobra/command.go

Lines 872 to 875 in 7039e1f

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

It may be interresting in some cases to be able to do some clean-up using a finalizer function.

[yann-soubeyrand]

I agree - this seems reasonable, but I think we're looking for a valid use case on this to keep the Cobra API thin: @yann-soubeyrand can you provide a small Cobra CLI program that would require this use case? Thanks much!

The program here https://github.com/yann-soubeyrand/cobra-test-2 has been initialized using cobra-cli init --viper which creates the initConfig function to load the configuration using viper. I’d like to have the ability to save the configuration at the end of the execution, hence my saveConfig function. It can be tested like this:

❯ touch ~/.cobra-test-2
❯ ./cobra-test-2 config get
Using config file: /home/yann/.cobra-test-2
<nil>
❯ ./cobra-test-2 config set
Using config file: /home/yann/.cobra-test-2
❯ ./cobra-test-2 config get
Using config file: /home/yann/.cobra-test-2
value

In this simple case, I arguably could have done the write of the config at the end or in the PostRun of my set command. However, in more complex programs where the configuration can be modified in several places, it’s useful to have a function which will be executed for sure at the end (unless there’s a panic or an explicit exit of course) which can be used to save the config.

[jpmcb]

Awesome! Been playing around with this and I do think it'll be useful. Thanks much for this!!