Allow calling package-initialize more than once

Allow calling package-initialize more than once

[Radon Rosborough]

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I would like to propose the following change, as a corollary to
previous changes to package initialization for Emacs 27:

| When `package-initialize' is first called, it acts as before; however,
| if it is called again, then it does nothing. This behavior can be
| overridden using a dynamically bound variable or an additional
| argument to `package-initialize'.

This change breaks backwards compatibility only in the following
case:

| Someone who already uses Emacs 27 intentionally calls
| `package-initialize' in their early init-file, then customizes
| `package-user-dir', then intentionally calls `package-initialize'
| again.

I am fairly confident that this use case has never been exercised by
anyone, so the change should be safe.

The benefit to making this change is that there is no need for people
to remove extraneous calls to `package-initialize' from their
init-file when upgrading from Emacs 26 to Emacs 27, and we may remove
the annoying warning introduced in [1] and discussed at [2].

If there are no objections, I would like to prepare a patch to
implement the change.

Best regards,
Radon Rosborough

[1]:
https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=2db57579b08ac99c464b6d3698648b3167fc5d55
[2]: https://lists.gnu.org/archive/html/emacs-devel/2018-02/msg00626.html

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Re: Allow calling package-initialize more than once

[Radon Rosborough]

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> If there are no objections, I would like to prepare a patch to
> implement the change.

Does the lack of comments mean I am good to go with this?

Thanks,
Radon

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Re: Allow calling package-initialize more than once

[Radon Rosborough]

Hi,

Is this plan good to go? I would like to get some acknowledgement
before I start writing code.

Thanks,
Radon

Re: Allow calling package-initialize more than once

[Clément Pit-Claudel]

On 2018-08-28 16:36, Radon Rosborough wrote:
> Hi,
> 
> Is this plan good to go? I would like to get some acknowledgement
> before I start writing code.

FWIW this change sounds useful to me.  I can't think of problems it might cause.
It might be good to still make no-op calls to package initialize print a message (but not a warning)?
Lastly, making the existing warning more explicit might be useful (see confusion on e.g. https://github.com/jkitchin/scimax/issues/194)

Re: Allow calling package-initialize more than once

[Radon Rosborough]

> It might be good to still make no-op calls to package initialize
> print a message (but not a warning)?

No, I think that defeats the purpose of this change. My idea is to
make it so that people are not bothered by the package.el changes in
Emacs 27 unless they are really doing something that absolutely does
require changes to their configuration.

> Lastly, making the existing warning more explicit might be useful

True, but removing it entirely will be better, I think.

Re: Allow calling package-initialize more than once

[Tom Tromey]

>>>>> "Radon" == Radon Rosborough <radon.neon@gmail.com> writes:

Radon> This change breaks backwards compatibility only in the following
Radon> case:

Radon> | Someone who already uses Emacs 27 intentionally calls
Radon> | `package-initialize' in their early init-file, then customizes
Radon> | `package-user-dir', then intentionally calls `package-initialize'
Radon> | again.

It seems like it also affects users who modify package-directory-list.

Perhaps you could just make package-initialize copy these values and
then do nothing if they have not changed.

Tom

Re: Allow calling package-initialize more than once

[Radon Rosborough]

> It seems like it also affects users who modify
> package-directory-list.

You are correct. The same is true of package-load-list, etc. I was
using package-user-dir as a stand-in for "any values which could be
changed to intentionally load two different sets of packages", and
should have been clearer about that.

> Perhaps you could just make package-initialize copy these values and
> then do nothing if they have not changed.

How about instead of trying to magically fix it, we signal a warning
like present, except only when the aforementioned variables have
changed between the two invocations of package-initialize?

That will solve the problem of ordinary users being unnecessarily
pestered about superfluous package-initialize calls, and also solve
the problem of things silently not working in advanced configurations.

Re: Allow calling package-initialize more than once

[Stefan Monnier]

>> Perhaps you could just make package-initialize copy these values and
>> then do nothing if they have not changed.
> How about instead of trying to magically fix it, we signal a warning
> like present, except only when the aforementioned variables have
> changed between the two invocations of package-initialize?

I think running package-initialize in those cases will better reproduce
the old behavior, so I think it's better to do that than to skip
running it.
But yes, it needs a warning in any case.


        Stefan