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RE: Different Methods inside one package

• To: mathgroup at smc.vnet.net
• Subject: [mg33727] RE: [mg33715] Different Methods inside one package
• From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
• Date: Wed, 10 Apr 2002 00:49:09 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

> -----Original Message-----
> From: J. Guillermo Sanchez [mailto:guillerm at usal.es]
To: mathgroup at smc.vnet.net
> Sent: Tuesday, April 09, 2002 7:03 AM
> Subject: [mg33727] [mg33715] [mg33715] Different Methods inside one package
> 
> 
> 
> (* Dear friends, I wish build a package where the user, as one option,
> can be choose one of three methods of evaluation, i.e: 
> Automatic, LT or 
> EV. Some thing like this silly example *)
> 
> BeginPackage["test`test`"]
> 
> methodTest::usage="methodTest. This is an example"
> 
> Options[methodTest]={Method\[Rule]Automatic};
> 
> Begin["`Private`"]
> 
> methodTest[matrixA_, incond_, opts___]:=
>   If[Automatic == Method/.{opts}/.Options[methodTest],
>     Module[{a, b, r},(a = matrixA; b = incond; r = a b)]]
> 
> methodTest[matrixA_, incond_, opts___]:=
>   If[LT == Method/.{opts}/.Options[methodTest],
>     Module[{a, b, r},(a = matrixA; b = incond; r = a /b)]]
> 
> methodTest[matrixA_, incond_, opts___]:=
>   If[EV == Method/.{opts}/.Options[methodTest],
>     Module[{a, b, r},(a = matrixA; b = incond; r = a + b)]]
> 
> End[]
> 
> Protect[methodTest];
> 
> EndPackage[]
> 
> list1 ={{a11, a12 },{a21,a22}}
> 
> methodTest[list1,list2]
> 
> methodTest[list1,list2, Method\[Rule]EV]
> 
> methodTest[list1,list2, Method\[Rule]LT]
> 
> 
> (*How can I get that this example work?*)
> 

Guillermo,

observe

In[15]:= BeginPackage["test`test`"]

methodTest::usage = "methodTest. This is an example";
LT::usage = "read manual";
EV::usage = "before operating";

Options[methodTest] = {Method -> Automatic};

Begin["`Private`"]

methodTest[matrixA_, incond_, opts___] := 
  Module[{a, b, r, m = Method /. Flatten[{opts}] /. Options[methodTest]},
    a = matrixA; b = incond;
    Which[
      m === Automatic, r = a b, 
      m === LT, r = a/b,
      m === EV, r = a + b,
      True, "something went wrong"]]

End[]

Protect[methodTest]

EndPackage[]

In[25]:= list1 = {{a11, a12}, {a21, a22}}

In[26]:= methodTest[list1, XXX]
Out[26]= {{a11 XXX, a12 XXX}, {a21 XXX, a22 XXX}}

In[27]:= methodTest[list1, XXX, Method -> EV]
Out[27]= {{a11 + XXX, a12 + XXX}, {a21 + XXX, a22 + XXX}}

In[28]:= methodTest[list1, XXX, Method -> LT]
Out[28]= {{a11/XXX, a12/XXX}, {a21/XXX, a22/XXX}}

In[29]:= ?LT
In[30]:= ?EV


Two things: first, if you repeat a definition (i.e. the same lhs of a
transformation rule), only the last one will be stored. Adding a condition
wouldn't work in your case however. Second, you must export your symbols
(LT, EV), otherwise global symbols will be inserted at call (and not be
recognized in the context "test`test`Private`")

In[33]:= Context[EV]
Out[33]= "test`test`"

--
Hartmut