When I try your code I'm told that 'mongo' is not a defined class. Removing
that field from the definition, I do not get a print on definition.
> mongoDbUser = setRefClass("mongoDbUser",
+ fields = list(
+ auth = "logical",
+ host = "character",
+ username = "character",
+ password = "character",
+ db = "character"
+ ),
+ methods = list(
+ initialize =
+ function(auth,host,username,password,db,connector){
+ print("initialization")
+ }
+ )
+ )
> R.Version()$version.string
[1] "R version 2.15.1 Patched (2012-06-22 r59603)"
So I guess there's more to the story.
In S4-land initialize methods can be tricky (e.g., invoked when an object is
coerced between types) and a common pattern is to write a constructor rather
than initialize methods
MongoDbUser <-
function(username, password, auth, host, db, connector)
{
## initialize, then
mongoDbUser$new(auth, host, username, password, db, connector
}
this also separates implementation from interface and provides the opportunity
to give hints to the user about data types
Martin Morgan
----- Original Message -----
> Help anyone? Is this impossible? I tried to use the initFields method
> but it did not change anything.
>
> Le 25/06/2012 10:55, Julien Cochennec a écrit :
> > Hi,
> > New to this list, and glad I found R5 which si a great improvement
> > to
> > R for my work.
> > Something seems odd anyway, when I do a setRefClass, the initialize
> > method execute at the class definition.
> > I would like it to execute only when an instance is created.
> > How can I do that? I found no way to test if the code execution is
> > when the class definition happens or when a $new instance is
> > created.
> > Thanks for your help.
> > For example my class definition looks like this :
> >
> > mongoDbUser = setRefClass("mongoDbUser",
> > fields = list(
> > auth = "logical",
> > host = "character",
> > username = "character",
> > password = "character",
> > db = "character",
> > connector = "mongo"
> > ),
> > methods = list(
> > initialize =
> > function(auth,host,username,password,db,connector){
> > print("initialization")
> > }
> > )
> > )
> >
> > If I execute this code, it says "initialization", but it shouldn't,
> > I
> > created no instance, right??
> > I would like "initialization" to appear only when I do :
> > mongoDbUser$new(...)
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
