Good to know. However, _please_ don't use the horrible kludge in the
attr(..) expression. From my experimenting, it worked fine just to say:
mtrace(edit, from = xx)
and even if that did not work, from = as.environment(xx) is identical in
effect to the attr() expression and means something. (Usually the
coercion to "environment" happens automatically.)
The attr() expression is strongly deprecated and very much not
guaranteed to work. First, it's discouraged to use the .xData slot,
which is part of the implementation and not part of the API. And ditto
to access _any_ slot by attr(), for the same reason.
However, in my experimenting the technique required xx$edit to have been
evaluated at some point before the call to mtrace(). Reference methods
are copied to the object when first required (for efficiency). Because
my workaround explicitly used xx$edit, the problem didn't arise. Just
evaluating xx$edit should be enough.
On the "before instantiated" point. I assume you mean in order to trace
the method in all objects generated from the reference class. I had
thought about that too. The same mechanism I described in my previous
mail works for this as well, but requires a kludge to get the
environment containing the methods. The steps I outlined are as before
but modified (in the example) as follows:
> mm = mEditor$def@refMethods
> edit = mm$edit
> trace(edit, browser, where = mm)
(mm is the environment with the methods). Then the objects generated by
mEditor$new() will have the traced version.
The same technique didn't seem to work for mtrace(), but a modification
might.
John
On 4/7/11 4:56 PM, mark.braving...@csiro.au wrote:
'mtrace' will work with reference classes, at least after an object is
instantiated. I'm not familiar with the guts of reference classes, but the
following quick experiment was successful.. If you run the example in
'?ReferenceClasses' up to& including this line :
xx<- mEditor$new(data = xMat)
and then do this:
mtrace( edit, from=attr( xx, '.xData'))
and then run the next line of the example, which is
xx$edit(2, 2, 0)
then the debug window will come up as normal.
Now, what about if you want to mtrace 'edit' before objects are instantiated?
Here the S4 structure defeated me temporarily, but I probably would have been
able to beat it if I'd had more time... There are some notes on debugging S4
methods in 'package?debug' (note that '?mtrace' itself is out-of-date on S4-- I
have gotten S4 debugging to work, but it's only described in 'package?debug')
and that might be enough to get you going.
HTH
Mark ('debug' package author)
Mark Bravington
CSIRO CMIS
Marine Lab
Hobart
Australia
________________________________________
From: r-devel-boun...@r-project.org [r-devel-boun...@r-project.org] On Behalf
Of A Zege [andre.z...@gmail.com]
Sent: 08 April 2011 05:00
To: r-devel@r-project.org
Subject: [Rd] How to debug reference classes?
How do you debug methods of a reference class? I've been using mtrace, which
is excellent, but i cannot figure out how to mtrace a reference class
method. Maybe there is some other way to debug these, for example with
ordinary trace? for now i am only able to use options(error=recover), which
is not giving me idea where exactly in the code i am once i am stopped on an
error.
--
View this message in context:
http://r.789695.n4.nabble.com/How-to-debug-reference-classes-tp3434269p3434269.html
Sent from the R devel mailing list archive at Nabble.com.
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