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  While the programming interface for the methods package follows the
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  While the programming interface for the methods package follows the
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  reference, the R software is an original implementation, so details in
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  reference, the R software is an original implementation, so details in
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  the reference that reflect the S4 implementation may appear
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  the reference that reflect the S4 implementation may appear
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  differently in R.  Also, there are extensions to the programming
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  differently in R.  Also, there are extensions to the programming
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  interface developed more recently than the reference.  For a
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  interface developed more recently than the reference.  For a
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  discussion of details and ongoing development, see the web page
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  discussion of details and ongoing development, see the web page
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  \url{http://developer.r-project.org/methodsPackage.html} and the
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  \url{http://developer.r-project.org/methodsPackage.html} and the
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  pointers from that page.
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  pointers from that page.
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}
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}
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\seealso{
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\seealso{
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  \link{Classes},
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  \link{Classes},
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  \code{\link{isClass}}.
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  \code{\link{isClass}}.
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}
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}
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\examples{
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\examples{
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getClass("numeric") ## a built in class
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getClass("numeric") ## a built in class
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cld <- getClass("thisIsAnUndefinedClass", .Force = TRUE)
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cld ## a NULL prototype
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## If you are really curious:
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\dontshow{
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str(cld)
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getClass("thisIsAnUndefinedClass", .Force = TRUE) ## returns NULL
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## Whereas these generate errors:
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try(getClass("thisIsAnUndefinedClass")) ## generates an error
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try(getClass("thisIsAnUndefinedClass"))
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try(getClassDef("thisIsAnUndefinedClass")) ## generates an error
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try(getClassDef("thisIsAnUndefinedClass"))
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}
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}
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}
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\keyword{programming}
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\keyword{programming}
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\keyword{classes}
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\keyword{classes}