[Rd] identical(..., ignore.environment=TRUE)

[Martin Maechler]

>>>>> William Dunlap <wdunlap at tibco.com>
>>>>>     on Tue, 13 Oct 2015 09:12:34 -0700 writes:

> MM> but I don't think we'd want to
> MM> change  all.equal.language()  at this point in time

> Although it would be nice if all.equal looked at least at attributes of
> formulas
> so we did not get results like

>   > form <- y ~ x1 %in% x2
>   > all.equal(form, terms(form))
>   [1] TRUE

>   > all.equal(terms(y~x1+x2+Error(x3/x2), specials="Error"),
>               terms(y~x1+x2+Error(x3/x2)))
>   [1] TRUE

Hmm...  of course, you have a very good point....

So,  let me say
"Patches are welcome!"
 (If
   - they include changes to the *.Rd files  [e.g., with an option
					      to remain back-bug-compatible]
   - are well tested, e.g., run   'make check-all' )


[Yes, I think I know why they probably won't come from you,
 Bill, unfortunately ..]

Martin


> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com

> On Tue, Oct 13, 2015 at 8:39 AM, Martin Maechler <maechler at stat.math.ethz.ch
> > wrote:

> > >>>>> Duncan Murdoch <murdoch.duncan at gmail.com>
> > >>>>>     on Mon, 12 Oct 2015 19:31:11 -0400 writes:
> >
> >     > On 12/10/2015 9:51 AM, Ben Bolker wrote:
> >     >> Duncan Murdoch <murdoch.duncan <at> gmail.com> writes:
> >     >>
> >     BB>
> >     >>>>> It seems odd/inconvenient to me that the
> >     >>>>> "ignore.environment" argument of identical() only
> >     >>>>> applies to closures (which I read as 'functions' --
> >     >>>>> someone can enlighten me about the technical
> >     >>>>> differences between functions and closures if they
> >     >>>>> like -- see below for consequences of my confusion).
> >     >>>>> This is certainly not a bug, it's clearly documented,
> >     >>>>> but it seems like a design flaw.  It would certainly
> >     >>>>> be convenient to be able to ignore differences in
> >     >>>>> environments when comparing complex objects with lots
> >     >>>>> of deeply nested formula and terms objects with
> >     >>>>> environments ...
> >     >>>>>
> >     >>>>> Can anyone suggest a reason for this design?
> >     >>>>>
> >     >>
> >     >> [snip]
> >     >>
> >     >>>>> Actually, maybe I don't understand how this is
> >     >>>>> supposed to work since I thought this would be TRUE:
> >     >>>>>
> > >>>>> f1 <- function() {}
> > >>>>> f2 <- function() {}
> > >>>>> environment(f1) <- new.env()
> > >>>>> environment(f2) <- new.env()
> > >>>>> identical(f1,f2,ignore.environment=TRUE) ## FALSE
> >     >>>>
> >     >>>> Those two functions likely have different srcref
> >     >>>> attributes.  If you created f2 using f2 <- f1, you'd
> >     >>>> get your expected result.
> >     >>>>
> >     >>
> >     >> [snip]
> >     >>
> >     >> Thanks for the clarification about closures
> >     >> vs. functions.
> >     >>
> >     >> [snip]
> >     >>
> >     >> You're right that the srcref attributes are different;
> >     >> although their bodies are the same, they have their own
> >     >> environments that differ.  For me, this makes the
> >     >> intended use of ignore.environment= even more puzzling;
> >     >> given that environments are not ignored recursively
> >     >> (that's not exactly what I mean -- I mean ignoring all
> >     >> environments of components of an object), I have trouble
> >     >> understanding the use case for ignore.environnment ...
> >     >> maybe it was developed before srcrefs existed?
> >
> >     > I think it simply means "ignore.environment.of.closures",
> >     > as the description says, but that's too long to be a
> >     > convenient arg name.
> >
> >     > Closures have three parts: the formals, the body and the
> >     > environment.  (Actually, 4 parts: like almost all R
> >     > objects, they may also have attributes.)
> >
> >     > That arg just says to ignore the environment part when
> >     > comparing closures.  It doesn't say to ignore environments
> >     > in general.
> >
> > For another beat on a dead horse, @ Ben:
> >
> > You could either use  options(keep.source = FALSE) in your
> > enviroment such that your functions should not have any 'srcref'
> > attributes anymore,
> >
> > or probably more sensible, use
> >
> > all.equal(f1, f2) rather than identical(f1, f2, ..)
> >
> > which I think should really do what you want
> > [even though it ends up using string comparison after deparse(.)
> >  .. about which one can debate... but I don't think we'd want to
> >  change  all.equal.language()  at this point in time].
> >
> > Martin
> >
> >
> >     >>
> >     >> In the R code base it's used in checkConflicts (to see if
> >     >> a function is re-exported) and in getAnywhere ...
> >     >>
> >
> >     > I'd say those uses are slightly bogus.  You should
> >     > generally remember that closures have 3 (or 4) parts, and
> >     > not go around comparing only two (or 3) of them.
> >
> >     > Duncan Murdoch
> >
> >     > ______________________________________________
> >     > R-devel at r-project.org mailing list
> >     > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >