[R] Missing arguments to new

[J Swinton]

Is this the expected and/or correct behaviour? And if
so, how do I persuade new to interpret a named but
missing argument as missing?

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setClass("testMissing",representation(a="numeric"),prototype=list(a=0));

showMissing <- function(real.arg,missing.arg) {
  really.missing <- new("testMissing");
  show(really.missing);
  really.there <- new("testMissing",a=1);
  show(really.there);
  arg.there <- new("testMissing",a=real.arg);
  show(arg.there);
  arg.missing <- new("testMissing",a=missing.arg);
  show(arg.missing);
}

> showMissing(real.arg=2)
An object of class "testMissing"
Slot "a":
[1] 0

An object of class "testMissing"
Slot "a":
[1] 1

An object of class "testMissing"
Slot "a":
[1] 2

Error in initialize(value, ...) : Argument
"missing.arg" is missing, with no default

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Jonathan Swinton

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Jonathan Swinton; jonathan at swintons.net

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