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Same name for functions in package and Global context


I am using a package that was written for Mathematica 3 while I am now working on Mathematica 8. I have issues with 2 functions in particular, Order and GraphComplement. They are a part of this package but are also present in Mathematica 8 by default but with distinctly different arguments and working. (I am assuming they weren't around in Mathematica 3)


Now when I make use of some other functions in this package they make calls to both Order and GraphComplement and it keeps trying to use the in built wolfram version. I instead want it to use the one that comes with the package.


Can anyone point me to the right direction?



Answer



If I understand the problem I think I can help, but what I propose is a bit weird. I think you have a package that uses the unqualified Symbol name Order internally, and you need the package not to see the System`Order Symbol while it is defined. To effect this you can temporarily change the Context of Order, then put it back after loading the package.



As an example here is a bare-bones package defining a function foo that uses an internal definition for Order:


BeginPackage["MyStuff`"]

foo::usage = "my function";

Begin["`Private`"]

Order[args___] := {args} === Sort[{args}];

foo[a_, b_] := If[Order[a, b], "Arguments are in order", "Arguments are out of order"]


End[]

EndPackage[]

After saving this to foo.m if I call Get[foo.m] and try to use foo I have a problem:


Get["foo.m"]

foo[1, 2]



SetDelayed::write: Tag Order in Order[args___] is Protected. >>


If[1, "Arguments are in order", "Arguments are out of order"]

But if, after restarting the kernel, I first move Order out of the System context before loading the package:


Context[System`Order] = "hold`";

Get["foo.m"]

Context[hold`Order] = "System`";


I can now call my foo as intended:


foo[1, 2]
foo[4, 2]


"Arguments are in order"

"Arguments are out of order"


This works because while the package is being defined Order is not found in the context path, and a new Symbol MyStuff`Private`Order is created and defined instead:


Definition[foo]


foo[MyStuff`Private`a_, MyStuff`Private`b_] := 
 If[MyStuff`Private`Order[MyStuff`Private`a, MyStuff`Private`b],
   "Arguments are in order",
   "Arguments are out of order"]

And Order still works elsewhere as its context is restored:



Order["a", "b"]


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