[Rd] actual argument matching does not conform to the definition (PR#13634)
tlumley at u.washington.edu
Thu Apr 2 14:39:23 CEST 2009
The explanation is that quote() is a primitive function and that the argument matching rules do not apply to primitives. That section of the R Language definition should say that primitives are excluded; it is documented in ?.Primitive.
On Thu, 2 Apr 2009 waku at idi.ntnu.no wrote:
> Full_Name: Wacek Kusnierczyk
> Version: 2.10.0 r48269
> OS: Ubuntu 8.04 Linux 32 bit
> Submission from: (NULL) (184.108.40.206)
> In the following example (and many other cases):
> # 1
> the argument matching is apparently incorrect wrt. the documentation (The R
> Language Definition, v 2.8.1, sec. 4.3.2, p. 23), which specifies the following
> algorithm for argument matching:
> 1. Attempt to match named actual arguments to formal arguments exactly.
> 2. For the arguments remaining from step 1, attempt to match named actual
> arguments to formal arguments partially.
> 3. For the arguments remaining from step 1, collectively match all unnamed
> actual arguments to the formal argument '...', if available.
> 4. If any arguments remain, declare an error.
> quote(a=1) qualifies for step 4:
> 1. The actual argument 'a' does not match exactly quote's only formal argument,
> 2. The actual argument 'a' does not match partially quote's only formal
> argument, 'expr'.
> 3. quote has no formal argument '...', hence 'a' remains unmatched.
> 4. An error should be raised.
> Instead, the actual argument 'a' is matched to the formal argument 'expr'. This
> clearly conflicts with the definition. Either the definition or the
> implementation (or both) are wrong.
> The problem is not constrained to quote, and seems to be ubiquitous (though does
> not apply to all functions).
> There are additional minor issues with the documentation which were raised in a
> separate thread.
> R-devel at r-project.org mailing list
Thomas Lumley Assoc. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle
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