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MathGroup Archive 2007

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Re: Two different packages can not Need[] the same utility package?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg79935] Re: [mg79867] Two different packages can not Need[] the same utility package?
  • From: "Benedek Kovács" <benedek.kovacs.mr at gmail.com>
  • Date: Thu, 9 Aug 2007 05:17:56 -0400 (EDT)
  • References: <200708070532.BAA12076@smc.vnet.net> <46B881A5.3050204@wolfram.com>

Hi

I have corrected the code according to your comments (the typo and the
BeginPackage). The result is different than it was. (I actually don't
understand why. According to the documentation
<<BeginPackage<http://reference.wolfram.com/mathematica/ref/BeginPackage.html>
["context`", {"need1`", "need2`", ...}] calls
Needs<http://reference.wolfram.com/mathematica/ref/Needs.html>on the
needi. >> BeginPackage["f`",{"something`"}] and
BeginPackage["f`"];Needs["something`"] has to result the same. Or am I
misunderstanding something?) Anyway, with the modified code the function "f"
didn't work either.

I have browsed the documentation and now I have another problem in close
connection to this. When I get Statistics`ContinuousDistributions`, a couple
of packages also will be in the $ContextPath, like
Statistics`NormalDistribution which I think has the definition for function:
NormalDistribution[x_,y_]. However, when I call the package with
BeginPackage["ff`",{"Statistics`ContinuousDistributions`"}], the
$ContextPath will not contain Statistics`NormalDistribution thus it is not
defined (not known by the kernel). How can this happen? I suppose that the
packages does not recursively Need each other. Is that right?

I have tried the following example:
*

BeginPackage["aa`"];Unprotect[a];Begin["Private`"];a[x_]:=x+1;End[];Protect[a];EndPackage;

BeginPackage["bb`",{"aa`"}];Unprotect[b];Begin["Private`"];b[x_]:=10
x;End[];Protect[b];EndPackage;

BeginPackage["cc`",{"bb`"}];Unprotect[c];Begin["Private`"];c[x_]:=x
x;End[];Protect[c];EndPackage;

$ContextPath
*

{cc*`,*bb`,System`}
Altough I have "Need"-ed aa` for bb` clearly.

What do you think?

Regards
Bence





On 8/7/07, Adam Berry <adamb at wolfram.com> wrote:
>
> Hello,
>
> you should declare the packages dependencies using the second argument
> of BeginPackage, for example;
>
> BeginPackage["foo`",{"Statistics`ContinuousDistributions`"}]
>
> This will solve the problem you are having, see the documentation for
> BeginPackage at
>
> http://reference.wolfram.com/mathematica/ref/BeginPackage.html
>
> Adam Berry
> Wolfram Research, Inc
>
> benedek.kovacs.mr at gmail.com wrote:
> > Hi
> >
> > Here is a problem a I face with:
> > I define two packages. Both needs the same
> > Statistics`ContinuousDistibutions` package. However, the second one
> > can not use it. Why? And how to resolve this problem?
> >
> > To make it more exact, in the following example I will define two
> > packages: ff and gg with the corresponding f and g functions both
> > using NormalDistribution. The first one evaluated works while the
> > second does not. the problem is even more disappointing if we Get[]
> > one packege twice and then are unable to use the function. More
> > complicated verisions can appear using the Sytem` functions or using
> > built-in packages where we does not even know what other packages are
> > invited.
> >
> > Does anyone have a solution for this problem?
> >
> > Kind Regards
> > Bence
> >
> > In[1]:=BeginPackage["ff`"]
> > Out[1]=ff`
> > In[2]:=Unprotect[f]
> > Out[2]={}
> > In[3]:=Begin["`Private`"]
> > Out[3]=ff`Private`
> > In[4]:=Needs["Statistics`ContinuousDistributions`"]
> > In[5]:=Options[f]:={MyDistributionFunction\[Rule](NormalDistribution[#,
> > 0.2 #]&)}
> > f[x_,opts___]:=Random[(MyDistributionFunction/.{opts}/.Options[f])[x]]
> > In[7]:=End[]
> > Out[7]=ff`Private`
> > In[8]:=Protect[f]
> > Out[8]={f}
> > In[9]:=EndPackage[]
> >
> > In[10]:=f[3]
> > Out[10]=2.16487
> > In[11]:=ff`f[3]
> > Out[11]=4.16217
> >
> > In[12]:=BeginPackage["gg`"]
> > Out[12]=gg`
> > In[13]:=Unprotect[g]
> > Out[13]={}
> > In[14]:=Begin["`Private`"]
> > Out[14]=gg`Private`
> > In[15]:=Needs["Statistics`ContinuousDistributions`"]
> > In[16]:=Options[g]:={MyDistributionFunction\[Rule]
> > (NormalDistribution[#,0.2 #]&)}
> > g[x_,opts___]:=Random[(MyDistributionFunction/.{opts}/.Options[f])[x]]
> > In[18]:=End[]
> > Out[18]=gg`Private`
> > In[19]:=Protect[g]
> > Out[19]={g}
> > In[20]:=EndPackage[]
> >
> > In[21]:=f[3]
> > Out[21]=2.88763
> > In[22]:=ff`f[3]
> > Out[22]=3.09767
> >
> > In[23]:=g[3]
> > >From In[23]:=\!\(\*
> >   RowBox[{\(Random::"randt"\), \(\(:\)\(\ \)\), "\<\"Type
> > specification \\!\\(
> >       gg`Private`MyDistributionFunction[3]\\) in \
> > \\!\\(Random[\\(\\(gg`Private`MyDistributionFunction[3]\\)\\)]\\)
> > should be \
> > Real, Integer, or Complex. \\!\\(\\*ButtonBox[\\\"More...\\\", \
> > ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \
> > ButtonData:>\\\"Random::randt\\\"]\\)\"\>"}]\)
> > Out[23]=Random[gg`Private`MyDistributionFunction[3]]
> > In[24]:=gg`g[3]
> > >From In[24]:=\!\(\*
> >   RowBox[{\(Random::"randt"\), \(\(:\)\(\ \)\), "\<\"Type
> > specification \\!\\(
> >       gg`Private`MyDistributionFunction[3]\\) in \
> > \\!\\(Random[\\(\\(gg`Private`MyDistributionFunction[3]\\)\\)]\\)
> > should be \
> > Real, Integer, or Complex. \\!\\(\\*ButtonBox[\\\"More...\\\", \
> > ButtonStyle->\\\"RefGuideLinkText\\\", ButtonFrame->None, \
> > ButtonData:>\\\"Random::randt\\\"]\\)\"\>"}]\)
> > Out[24]=Random[gg`Private`MyDistributionFunction[3]]
> >
> >
>



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