Full_Name: Wacek Kusnierczyk Version: 2.10.0 r48269 OS: Ubuntu 8.04 Linux 32 bit Submission from: (NULL) (129.241.199.164) In the following example (and many other cases): quote(a=1) # 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, 'expr'. 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. Regards, vQ
actual argument matching does not conform to the definition (PR#13634)
3 messages · Thomas Lumley, Wacek Kusnierczyk
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.
-thomas
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) (129.241.199.164) In the following example (and many other cases): quote(a=1) # 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, 'expr'. 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. Regards, vQ
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Thomas Lumley Assoc. Professor, Biostatistics tlumley at u.washington.edu University of Washington, Seattle
Thomas Lumley wrote:
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.
thanks. indeed, the documentation -- the language *definition* --
should make this clear. so this is a bug in the definition, which does
not match the implementation, which in turn is as intended (right?)
?.Primitive says:
" The advantage of '.Primitive' over '.Internal' functions is the
potential efficiency of argument passing. However, this is done
by ignoring argument names and using positional matching of
arguments (unless arranged differently for specific primitives
such as 'rep'), so this is discouraged for functions of more than
one argument.
"
what is discouraged?
vQ