Skip to main content

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"]


1

Comments

Post a Comment

Popular posts from this blog

front end - keyboard shortcut to invoke Insert new matrix

I frequently need to type in some matrices, and the menu command Insert > Table/Matrix > New... allows matrices with lines drawn between columns and rows, which is very helpful. I would like to make a keyboard shortcut for it, but cannot find the relevant frontend token command (4209405) for it. Since the FullForm[] and InputForm[] of matrices with lines drawn between rows and columns is the same as those without lines, it's hard to do this via 3rd party system-wide text expanders (e.g. autohotkey or atext on mac). How does one assign a keyboard shortcut for the menu item Insert > Table/Matrix > New... , preferably using only mathematica? Thanks! Answer In the MenuSetup.tr (for linux located in the $InstallationDirectory/SystemFiles/FrontEnd/TextResources/X/ directory), I changed the line MenuItem["&New...", "CreateGridBoxDialog"] to read MenuItem["&New...", "CreateGridBoxDialog", MenuKey["m", Modifiers-...
Post a Comment
Read more

How to thread a list

I have data in format data = {{a1, a2}, {b1, b2}, {c1, c2}, {d1, d2}} Tableform: I want to thread it to : tdata = {{{a1, b1}, {a2, b2}}, {{a1, c1}, {a2, c2}}, {{a1, d1}, {a2, d2}}} Tableform: And I would like to do better then pseudofunction[n_] := Transpose[{data2[[1]], data2[[n]]}]; SetAttributes[pseudofunction, Listable]; Range[2, 4] // pseudofunction Here is my benchmark data, where data3 is normal sample of real data. data3 = Drop[ExcelWorkBook[[Column1 ;; Column4]], None, 1]; data2 = {a #, b #, c #, d #} & /@ Range[1, 10^5]; data = RandomReal[{0, 1}, {10^6, 4}]; Here is my benchmark code kptnw[list_] := Transpose[{Table[First@#, {Length@# - 1}], Rest@#}, {3, 1, 2}] &@list kptnw2[list_] := Transpose[{ConstantArray[First@#, Length@# - 1], Rest@#}, {3, 1, 2}] &@list OleksandrR[list_] := Flatten[Outer[List, List@First[list], Rest[list], 1], {{2}, {1, 4}}] paradox2[list_] := Partition[Riffle[list[[1]], #], 2] & /@ Drop[list, 1] RM[list_] := FoldList[Transpose[{First@li...
Post a Comment
Read more

mathematical optimization - Minimizing using indices, error: Part::pkspec1: The expression cannot be used as a part specification

I want to use Minimize where the variables to minimize are indices pointing into an array. Here a MWE that hopefully shows what my problem is. vars = u@# & /@ Range[3]; cons = Flatten@ { Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; Minimize[{Total@((vec1[[#]] - vec2[[u[#]]])^2 & /@ Range[1, 3]), cons}, vars, Integers] The error I get: Part::pkspec1: The expression u[1] cannot be used as a part specification. >> Answer Ok, it seems that one can get around Mathematica trying to evaluate vec2[[u[1]]] too early by using the function Indexed[vec2,u[1]] . The working MWE would then look like the following: vars = u@# & /@ Range[3]; cons = Flatten@{ Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; NMinimize[ {Total@((vec1[[#]] - Indexed[vec2, u[#]])^2 & /@ R...
Post a Comment
Read more