R help - Mar 2006 - Accessing functions in a library

I am trying to write a modified function to plot an rpart object.  By
using getS3method I can see the plot and text code that I want to
modify.  Since I don't want to modify the package, I create a new
function to plot the rpart object.  The problem is that the original
function calls many rpart specific functions that are only visible
inside the rpart namespace.  Therefore, when I call my modified function
it does not find the rpart specific functions and gives me an error.
How can I make a new function that is a small modification of an
existing package function and let the modified function access the
hidden package functions?

 

Michael Conklin

Chief Methodolgist - Advanced Analytics

 

MarketTools, Inc.

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Minneapolis, MN 55426

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Michael.Conklin@markettools.com <mailto:Michael.Conklin@markettools.com>


 

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"Michael Conklin" <michael.conklin at markettools.com> writes:
> I am trying to write a modified function to plot an rpart object.  By
> using getS3method I can see the plot and text code that I want to
> modify.  Since I don't want to modify the package, I create a new
> function to plot the rpart object.  The problem is that the original
> function calls many rpart specific functions that are only visible
> inside the rpart namespace.  Therefore, when I call my modified function
> it does not find the rpart specific functions and gives me an error.
> How can I make a new function that is a small modification of an
> existing package function and let the modified function access the
> hidden package functions?
You can subvert namespace protection using ":::".  So if there is a
hidden function g in package foo, use foo:::g().