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wolfram-mathematicamathematical-packages

Getting started with Mathematica packages

Can someone offer some advice on how to get started with mathematica packages?

I can save the following in a file named "Foo.m". When I run the input cell in that file, I can see the effects reflected in $ContextPath variable.

BeginPackage["Foo`"]

bar::usage = "barfunction";

Begin["`private`"]
bar[w_] := w;
End[];

EndPackage[];

However, in my notebook I have the following:

#include<foo>
SetDirectory[ToFileName[{$HomeDirectory, "My Documents", "mathematica"}]];
Needs["Foo`"]
$ContextPath

But the needs call is failing for some reason, and the $ContextPath remains unchanged.

Edit

I believe that I've got a partial solution working now, the cell in my file wasn't marked as an initialization cell - and whilst I can now <<Foo', Needs["Foo"]` still isn't working correctly.

Solution

  • Check to make sure the saved file, "Foo.m", is on your $Path, which tells Mathematica which directories to look in when trying to load packages, much like the PATH environment variable in Unix or Windows.

    EDIT: $ContextPath won't be changed unless there's an actual BeginPackage statement (or you manipulate it directly using Set or Block or something).

    EDIT the second: One thing to check is what 

    FileNames["Foo.m", $Path]

    returns. What you're describing does sound a little strange, though.