R devel - Oct 2004 - user interface and documentation of setIs and setAs, some suggestions (S4).

By reading the documentation for _setIs_ I noted that for the same 
object three different names are used.

1) the name of the first argument in the functions coerce and replace in 
setIs must be _obj_ (see example section or)
setIs("MVCa","list",coerce=function(obj){obj@list},replace=function(obj,value){obj@list<-value})


2) At the same time in the usage section:
setIs(class1, class2, test=NULL, coerce=NULL, replace=NULL,
           by = character(), where = topenv(parent.frame()), classDef =,
           extensionObject = NULL, doComplete = TRUE)
3) and finally in the argument section:
    the object to 'class2', and to alter the object so that
          'is(object, class2)' is identical to 'value'.

I much more like how setAs is implemented, we cast _from_  _to_  and so 
the arguments in all this functions are named. Its much more consistent.

I would also suggest to replace the keyword _def_ in the setAs function 
by _coerce_ as it is in the setIs function.
I thinke it will be nicer if bot methods will have a unified user 
interface if possible. Of corse it may be that this is not possible for 
reasons not known to me. In this case sorry.

/E

-- 
Dipl. bio-chem. Witold Eryk Wolski         
MPI-Moleculare Genetic
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