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Confusion about how certain keywords behave #1082

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sellout opened this issue Sep 23, 2024 · 2 comments
Open

Confusion about how certain keywords behave #1082

sellout opened this issue Sep 23, 2024 · 2 comments

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@sellout
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sellout commented Sep 23, 2024

I think this is a documentation issue, because I can’t seem to figure out what I can expect from certain keywords.

tl;dr: I think a flow chart of some sort would really help me understand which keywords fire when.

For example,

(use-package foo
  :defer t
  :init (foo-global-mode) ; assume this is defined with `autoload`

The docs say “Use the :init keyword to execute code before a package is loaded”, but what does “before a package is loaded” mean? Will :init fire linearly when the use-package is encountered, or will it wait until something else forces the loading of this package?

What I expect this form to do is execute the :init immediately, which will then cause the package to be loaded (without use-package handling the loading). The actual situation I have is that I have use-package-always-defer t, and I’m wondering if I can expect packages to be loaded because of the autoloads on their init form.

Or should I be doing something else re: loading packages? The examples in the README show a lot of examples like

(use-package foo
  :config (foo-global-mode t)

but that seems backward to me. It should be the package-defined autoload that causes a call to (foo-global-mode) to load the package (but I get that there’s not a lot of difference without :defer).

Similarly, how does :after interact with :init? This somewhat depends on the answer to the previous question, but assuming :init normally fires immediately, does :after defer it until after its dependencies are loaded, or will it still fire immediately?

(use-package bar
  :after foo
  :init (bar-global-mode)

(use-package foo
  :custom (foo-var t))

Does bar-global-mode get run before or after foo-var is set? And, if it‘s after, I assume that that’s no longer true if there’s a (require 'foo) above (use-package bar …, right?

Sorry for this rambling description. I just come up with these questions time and time again when I’m working on my config, and sometimes bother to trace through the code to see what’s happening and sometimes don’t, but it seems like it should be more obvious. I have more questions like this, but I’m hoping it’s possible to include a somewhat comprehensive description of all of these things without enumerating more of the specific confusions I’ve had.

@sellout
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sellout commented Sep 23, 2024

Sorry, one more specific question …

(require 'foo)

(use-package 'bar
  :after foo
  :custom (bar-var foo-var)) ; default is nil

(use-package foo
  :custom (foo-var t)) ; default is nil

Will bar-var be t or nil at the end of this? I’m pretty sure it’ll be nil, because :after only observes whether a package is loaded, not whether its use-package form has been evaluated, right? So :after isn’t necessarily that good at enforcing order-independence. In practice this often comes up because some other non-deferred package contained a (require 'foo).

So, I think the documentation of :after needs to be clarified a bit around that.

I feel like I’m being really critical here, so I just want to say that I understand that is is complicated, and use-package is a fantastic project.

@Mango0x45
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Use-Package has been incorporated into Emacs proper so this repository is mostly dead. You should try asking your questions on the Emacs mailing list.

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