How to get the directory of a package?

How to get the directory of a package?

[Marcin Borkowski]

Hello,

assume that I'm writing a package which wants to use a file from the
same directory the .el (or .elc) file of the package is located in.  How
can the package know where in the filesystem it is located?

Bonus points for a method which works not only with `require', but also
with `load-file' and `eval-buffer' (in the last case,
`default-directory' will probably work, but I skimmed through all
variables and functions matching `directory$' and nothing seemed to be
what I'm looking for).

TIA,

-- 
Marcin Borkowski
http://mbork.pl

Re: How to get the directory of a package?

[Marcin Borkowski]

OK,

> assume that I'm writing a package which wants to use a file from the
> same directory the .el (or .elc) file of the package is located in.  How
> can the package know where in the filesystem it is located?
>
> Bonus points for a method which works not only with `require', but also
> with `load-file' and `eval-buffer' (in the last case,
> `default-directory' will probably work, but I skimmed through all
> variables and functions matching `directory$' and nothing seemed to be
> what I'm looking for).

so I think I've found the answer.  Is this correct?  Are there possibly
some edge cases I didn't think about?

--8<---------------cut here---------------start------------->8---
(if load-file-name
    (file-name-directory load-file-name)
  default-directory)
--8<---------------cut here---------------end--------------->8---

TIA,

--
Marcin Borkowski
http://mbork.pl

Re: How to get the directory of a package?

[Stefan Monnier]

> (if load-file-name
>     (file-name-directory load-file-name)
>   default-directory)

That looks right to me,


        Stefan

Re: How to get the directory of a package?

[Eric Abrahamsen]

Marcin Borkowski <mbork@mbork.pl> writes:

> OK,
>
>> assume that I'm writing a package which wants to use a file from the
>> same directory the .el (or .elc) file of the package is located in.  How
>> can the package know where in the filesystem it is located?
>>
>> Bonus points for a method which works not only with `require', but also
>> with `load-file' and `eval-buffer' (in the last case,
>> `default-directory' will probably work, but I skimmed through all
>> variables and functions matching `directory$' and nothing seemed to be
>> what I'm looking for).
>
> so I think I've found the answer.  Is this correct?  Are there possibly
> some edge cases I didn't think about?
>
> (if load-file-name
>     (file-name-directory load-file-name)
>   default-directory)

I stole the following bit of code to find "this file" from 'ert-x, it
was a bit of cargo-culting as I'm not entirely sure when/how the various
conditions would be true:

(or (bound-and-true-p byte-compile-current-file)
    (and load-in-progress load-file-name)
    buffer-file-name)

Might be helpful?