On Nov 23, 2012, at 12:35 PM, Sam Steingold wrote:
* R. Michael Weylandt <zvpunry.jrlyn...@tznvy.pbz> [2012-11-23
09:13:36 +0000]:
2. because difftime.summary returns a data.frame and not a
"Classes 'summaryDefault', 'table'" as I assume summary must return.
See
http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-should-I-write-summary-methods_003f
what are the requirements on the class summary.foo?
I'm not sure it makes sense to frame the question this way.
summary.foo would nt be a class but rather a 'summary' method/function
that applied to items of class 'foo.
does it have to inherit from some other class?
There is implicit inheritance from the vector "class" and sometimes
default methods will assume a numeric vector. But if you defin an
object to be of a particular class, it would not need to have an
explicit inheritance defined/
how do I define a class?
That's pretty easy. Read:
?class # and the pages to which it links.
(And also read ?methods, and the pages to which it links. Then read
Sect 5 Object-oriented programming in the "R Language Definition".)
--
David Winsemius, MD
Alameda, CA, USA
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