On 11/06/2012 07:03 AM, Simon Knapp wrote:
I don't understand why I get the following results. I define two classes
'Base' and 'Derived', the latter of which 'contains' the first. I then
define a generic method 'test' and overload it for each of these classes. I
call 'callNextMethod()' in the overload for Derived. From the output, it
appears that the overload for Base gets called twice. Why is this? Test
code follows:
setClass('Base')
setClass('Derived', contains='Base')
setGeneric('test', function(x) standardGeneric('test'))
setMethod('test', signature(x='Base'), function(x) print('base called'))
setMethod('test', signature(x='Derived'), function(x) {print('derived
called'); callNextMethod()})
d = new('Derived')
test(d)
Produces the output:
[1] "derived called"
[1] "base called"
[1] "base called"
Fun; I think you're seeing the print command, and also the (normally invisible)
return value from print
> d = new('Derived')
> res = test(d)
[1] "derived called"
[1] "base called"
> res
[1] "base called"
similar to
> print("x")
[1] "x"
> (print("x"))
[1] "x"
[1] "x"
Martin
and I was expecting:
[1] "derived called"
[1] "base called"
Thanx in advance,
Simon Knapp
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