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19087 jmc 1 
\name{BasicClasses}
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\docType{class}
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\alias{character-class}
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\alias{complex-class}
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\alias{double-class}
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\alias{expression-class}
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\alias{externalptr-class}
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\alias{integer-class}
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\alias{list-class}
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\alias{logical-class}
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\alias{numeric-class}
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\alias{single-class}
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\alias{vector-class}
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\alias{NULL-class}
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\alias{function-class}
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\alias{ANY-class}
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\alias{VIRTUAL-class}
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\alias{missing-class}
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\title{Classes Corresponding to Basic Data Types }
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\description{
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  Formal classes exist corresponding to the basic R data types, allowing
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  these types to be used in method signatures, as slots in class
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  definitions, and to be extended by new classes.}
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\usage{
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### The following are all basic vector classes.
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### They can appear as class names in method signatures,
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### in calls to as(), is(), and new().
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"character"
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"complex"
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"double"
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"expression"
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"integer"
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"list"
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"logical"
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"numeric"
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"single"
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### the class
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"vector"
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### is a virtual class, extended by all the above
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### The following are additional basic classes
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"NULL"     #  NULL objects
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"function" #  function objects, including primitives
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"externalptr" # raw external pointers for use in C code
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"ANY"  # virtual classes used by the methods package itself
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"VIRTUAL"
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"missing"
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}
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\section{Objects from the Classes}{
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  Objects can be created by calls of the form \code{new(Class, ...)},
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  where \code{Class} is the quoted class name, and the remaining
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  arguments if any are objects to be interpreted as vectors of this
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  class.  Multiple arguments will be concatenated.
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  The class \code{"expression"} is slightly odd, in that the \dots
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  arguments will \emph{not} be evaluated; therefore, don't enclose them
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  in a call to \code{quote()}.
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}
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\section{Extends}{
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  Class \code{"vector"}, directly.
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}
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\section{Methods}{
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  \describe{
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    \item{coerce}{Methods are defined to coerce arbitrary objects to
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      these classes, by calling the corresponding basic function, for
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      example, \code{as(x, "numeric")} calls \code{as.numeric(x)}. }
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  }
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}
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\keyword{classes}