>>>>> Duncan Murdoch <murdoch.dun...@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
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