Le 17/11/10 13:07, Janko Thyson a écrit :
Hi there,
I'd like to choose between an "static" and "dynamic" access of a reference
class field, say 'a'.
myObj<- getRefClass("Blabla")$new()
Static: myObj$a
Dynamic: myObj$a.get() where the function retrieves the data
from a database (or some other location), stores it to a buffer and
optionally updates the static field value 'a'.
I've set up such a method 'a.get()' where I can actually decide between
static and dynamic runmode (so the method also wraps the call 'myObj$a' for
the static runmode).
Now I saw that setting up such accessor methods (get/set) is already done
for me if I use 'getRefClass("Blabla")$accessors(.)'. I just don't
understand what exactly I have to do there, because this results in an
error: 'getRefClass("Blabla")$accessors("a")'
Can anyone point me to the correct use of 'getRefClass(.)$accessors(.)'?
Thanks a lot,
Janko
Hi,
fields can either be data or active binding functionss. See
?makeActiveBinding for some example of active binding functions in their
original context.
Here is an example of a reference class that keeps its data in a file.
require( methods )
Foo <- setRefClass( "Foo",
fields = list(
file = "character",
x = function(value){
if( missing( value ) ){
read.table( file )
} else{
write.table( value, file = file )
}
}
)
)
foo <- Foo$new( file="/tmp/iris.txt" )
foo$x <- iris
foo$x
write.table( subset( iris, Petal.Length < 2), file = "/tmp/iris.txt" )
foo$x
Does that help ?
Romain
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Romain Francois
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