On 5/20/16 12:40 PM, Mick Jordan wrote:
I'm confused by this:
> identical(function() {}, function() {})
[1] FALSE
Yet, after loading the Matrix package (which redefines det), the
following is checked (in library.checkConflicts):
> identical(get("det", baseenv()), get("det", asNamespace("Matrix")),
ignore.environment=T)
[1] TRUE
I've looked at the code in identical.c and for closures it seems to
compare the FORMALS and the BODY_EXPR, so why does the first example
not return TRUE as surely the formals and body are identical?
case CLOSXP:
return(R_compute_identical(FORMALS(x), FORMALS(y), flags) &&
R_compute_identical(BODY_EXPR(x), BODY_EXPR(y), flags) &&
(IGNORE_ENV || CLOENV(x) == CLOENV(y) ? TRUE : FALSE) &&
(IGNORE_BYTECODE || R_compute_identical(BODY(x), BODY(y),
flags))
);
R-3.2.4, Mac OS X El Capitan
Ok, I figured it out, but this is VERY unintuitive IMHO:
> identical(attributes(function() {}), attributes(function() {}))
[1] FALSE
>
The srcref attribute (obviously) differs.
Mick Jordan
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