>>>>> "JMC" == John Chambers <[EMAIL PROTECTED]>
>>>>> on Tue, 07 Mar 2006 16:33:59 -0500 writes:
JMC> Martin Morgan wrote:
>> Thanks John for the reply and explanation. I sometimes
>> use validObject interactively, and in those circumstances
>> it might be nice to be able to require recursive validity
>> checking, e.g., with an optional argument.
>>
>>
JMC> Sounds reasonable. After some complicated replacements
JMC> of slots at various levels, it would make sense to do a
JMC> more complete test, and it does have to be done
JMC> explicitly.
JMC> It looks straightforward to have an argument complete=
JMC> that defaults to FALSE; if so, I'll add it to r-devel.
I agree with the other Martin that this would be "nice" to have.
Also for debugging purposes, or as "watch point" when developing
new functionality.
Martin Maechler, ETH Zurich
>> Martin
>>
>> John Chambers <[EMAIL PROTECTED]> writes:
>>
>>
>>
>>> The problem is over-ambitious documentation.
>>> Recursively running the checks on slots for all
>>> validObject calls would be a fairly serious efficiency
>>> hit. Objects are checked for validity when created,
>>> other than as the default object, so assuming the slot
>>> objects to be as claimed is reasonable if they haven't
>>> been corrupted later on. We'll update the
>>> documentation.
>>>
>>> Validity checking is a tricky business in general. R
>>> validates new objects, but users can turn valid objects
>>> into invalid objects in cases where slots have to match
>>> in special ways (you can't apply validObject each time a
>>> slot changes, since the change may be part of a bigger
>>> computation that _will_ produce a valid object).
>>> Similarly, constraints on the elements can't be checked
>>> each time an element or subset of the object changes, if
>>> the changes have to be done in stages. Systems that
>>> "commit" top-level assignments can check then, but R
>>> does not have that distinction.
>>>
>>> Martin Morgan wrote:
>>>
>>> The documentation for validObject suggests that slots
>>> are checked for validity, but validObject seems only to
>>> check that the slot has something claiming to be
>>> correct; validObject(obj) does not perform the
>>> equivalent of validObject([EMAIL PROTECTED]) for slot y.
>>>
>>> This is also the second problem issue reported in
>>>
>>> http://tolstoy.newcastle.edu.au/R/devel/05/03/0151.html
>>>
>>> Relevant documentation, an example, and sessionInfo
>>> follow.
>>>
>>> Martin
>>>
>>> validObject package:methods R Documentation
>>>
>>> Arguments: ... Note that validity methods do not have
>>> to check validity of any slots or superclasses: the
>>> logic of 'validObject' ensures these tests are done once
>>> only. ... Details:
>>>
>>> Validity testing takes place "bottom up": first the
>>> validity of the object's slots, if any, is tested. ...
>>>
>>> setClass("foo", representation( x="numeric" ), validity
>>> = function( object ) [EMAIL PROTECTED] > 0 ) setClass("bar",
>>> representation( y="foo", z="numeric" ), validity =
>>> function( object ) [EMAIL PROTECTED] > 0 ) obj <- new( "bar", y =
>>> new( "foo", x=1 ), z = 1 )
>>>
>>> and then...
>>>
>>>
>>>
>>> validObject( obj )
>>>
>>>
>>>
>>> [1] TRUE ## invalidate [EMAIL PROTECTED]
>>>
>>>
>>> [EMAIL PROTECTED]@x <- -1 validObject( [EMAIL PROTECTED] ) # right,
this is not
>>> valid
>>>
>>>
>>>
>>> Error in validObject([EMAIL PROTECTED]) : invalid class "foo"
>>> object: FALSE
>>>
>>>
>>> ## [EMAIL PROTECTED] is invalid, but obj is valid? validObject( obj
>>> ) # should be invalid?
>>>
>>>
>>>
>>> [1] TRUE
>>>
>>>
>>>
>>>
>>>
>>> sessionInfo()
>>>
>>>
>>>
>>> Version 2.3.0 Under development (unstable) (2006-03-03
>>> r37471) x86_64-unknown-linux-gnu
>>>
>>> attached base packages: [1] "methods" "stats" "graphics"
>>> "grDevices" "utils" "datasets" [7] "base"
>>>
>>> ______________________________________________
>>> R-devel@r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>>
>>>
>>>
>> ______________________________________________
>> R-devel@r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>
>>
JMC> [[alternative HTML version deleted]]
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