Thierry Volpiatto <thievol@posteo.net> writes:

> Philip Kaludercic <philipk@posteo.net> writes:
>
>>> No don't worry, helm will work in any cases, thanks.
>>
>> OK, in that case I'd prefer to keep it the way it is.
>
> Ok, fair enough.
>
>>>> Mainly to avoid issues with packages that might place files in the
>>>> configuration directory, which might hinder the reproduction of bugs.
>>>
>>> Hmm, maybe, I don't have an example in mind though.
>>
>> It might not be the best example, but my package autocrypt generates a
>> file in the `user-emacs-directory'.  If we don't use --init-directory,
>> the existing file would be re-used.
>
> Ok, for such case it is easy to either rename the file temporarily to
> foo_ori or foo_save or to set the variable handling the file (generally
> it is not harcoded) to something else. But another issue is if your
> isolated package needs the history file or tramp file or whatever file
> ~/.emacs.d is handling; e.g. a package providing completion on history.
> I still think it is more handy to reuse user-emacs-directory and its
> elpa directory where the packages are already installed.

How about this patch, that will use a temporary directory when
`package-isolate' is invoked with a prefix argument (not sure what the
default should be, I guess reusing `user-emacs-directory' is less
surprising):