Re: How to find out which directory a .m file is loaded from?
- To: mathgroup at smc.vnet.net
- Subject: [mg38936] Re: [mg38922] How to find out which directory a .m file is loaded from?
- From: Todd Gayley <tgayley at wolfram.com>
- Date: Tue, 21 Jan 2003 07:38:14 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
At 11:33 PM 1/18/03, John Harper wrote:
>I'd like, in a .m file for a package, to be able to know what directory
>the .m file is being loaded from, so I can search in the same place
>(or subdirectories) for related files. I've looked through everything
>to do with directories I can find in The Book, but I can't find anything
>that looks as though it would help.
>
>Anyone know how to do this? Thanks in advance...
>
> John
John,
There is a nice trick for this. It works on every operating system and all
versions of Mathematica from at least 4.0 onward (and probably earlier). It
uses the undocumented function System`Private`FindFile, but if that ever
goes away we'll have to add something to take its place because J/Link uses
this exact technique to find its application resources.
Put a line like this in your .m file:
thisPackageDirectory = DirectoryName[System`Private`FindFile[$Input]]
The variable thisPackageDirectory will get the directory name in which the
.m file resides no matter how the user reads the package, e.g.:
<<MyPackage.m
<</full/path/to/MyPackage.m
<<MyPackage`
Needs["MyPackage`"]
etc.
This trick also works if you use the standard Mathematica application
directory structure (highly recommended), wherein you have a directory
named for your package (say MyApp):
<Mathematica dir>/
Applications/
MyApp/
MyApp.m
... other files and dirs ...
Kernel/
init.m <-- this file reads simply: Get["MyApp`MyApp`"]
This standard application layout allows users to enter simply
Needs["MyApp`"]
to load your MyApp.m file. The thisPackageDirectory variable would then get
the value "<Mathematica dir>/Applications/MyApp".
Todd Gayley
Wolfram Research