R help - Aug 2012 - OO code organization

Greetings,
 
I am using S4 classes and the code is organized by putting each class into a
separate source file
in a separate folder:
 
In Folder base/base.R:    defines class "base" and does
 
setGeneric("showSelf",
    function(this) standardGeneric("showSelf")
)
setMethod("showSelf",
signature(this="base"),
definitionfunction(this){ ... }
)
 
 
 
For j=1,...,n:
in  derived_j/derived_j.R:   defines class "derived_j" and does
 
setMethod("showSelf",
signature(this="derived_j"),
definitionfunction(this){ ... }
)
 
Finally in tests/tests.R    we do
 
source("../base/base.R")
source("../derived_1/derived_1.R")
source("../derived_2/derived_2.R")
....
source("../derived_n/derived_n.R")
 
 now we check which methods "showSelf" are known at this point:
 
showMethods("showSelf")
 
and get
>showMethods("showSelf")
Function: showSelf (package .GlobalEnv)
this="base"
this="derived_n"
 
 
 
The methods with signature 
this="derived_j",  j<n
are not known.
 
Needless to say this makes the code useless.
How can I remedy this evil?
 
Many thanks,
 
Michael Meyer
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Greetings,
 
I found the mistake. As this may be useful to others the details are as follows:
 
In the source file 
    derived_j/derived_j.R
of every derived class the source of the base 
    source("..base/base.R")
was included (as you would in C or C++).
This file contains the statement
setGeneric("showsSelf",...)
 
However when doing in file tests/test.R
 
source("../base/base.R")source("../derived_1/derived_1.R")source("../derived_2/derived_1.R")
....source("../derived_n/derived_1.R")
 
the repeated evaluation ofsetGeneric("showsSelf",...)
is triggered.
 
Apparently after each such call to setGeneric the slate is wiped clean
and the previous definitions for methods of the generic deleted.
Thus only the last definition in 
 
 
source("../derived_n/derived_1.R")
survives.
The inclusion of source("..base/base.R") is not needed
and removal cures the problem.
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