Example of Using an S3 Class in a S4 Object

Question

I want to include an RODBC connection as part of S4 object. It looks like RODBC is S3. For example:

setClass(
  Class="Node",
  representation=representation(
    nodeName = "character",
    connection = "RODBC"
  )                    
)

Throws undefined slot classes. It looks like I want to use setOldClass, but I am having trouble figuring out how to use it. Assuming I do want setOldClass, How would I use setOldClass so that I can include my RODBC connection as slot to my Node class?

Is it as simple as: `setOldCass("RODBC")` and then just exactly what I have above? If so I feel a bit sheepish ... — Kyle Brandt, Jan 30 '12 at 16:53

Kyle Brandt · Accepted Answer · 2012-01-31T21:48:47.227

7

Although the documentation is quite involved for this function, if all you need to do include the class in a slot it is as simple as:

setOldClass("RODBC")

setClass(
  Class="Node",
  representation=representation(
    nodeName = "character",
    connection = "RODBC"
  )                    
)

This is also what you would use for reference classes.

edited Jan 31 '12 at 21:48

answered Jan 30 '12 at 17:19

Kyle Brandt

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It will not work when I use roxygen2 to document it. If I put `setOldClass("RODBC")` into a single file. When checking, it will be "the specification for S3 class “dist” in package seems equivalent to one from package ‘graph’: not turning on duplicate class definitions for this class." – Zhilong Jia Mar 06 '15 at 14:53

Example of Using an S3 Class in a S4 Object

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