[R] Error with named definition argument to match.call

[David Winsemius]

On Jul 15, 2014, at 5:04 PM, William Dunlap wrote:

> Does it make sense to call match.call outside of a function without
> specifying both the function definition and the call to the function?

My puzzlement came from the different response to these two commands:

match.call(g)
match.call(definition=g)

I thought they would be the same. So you are saying to make sense this  
would need to be

 > match.call(definition=g , call=quote(g(1)) )
g(x = 1)



-- 
David.

> I agree that the error message is misleading.  Also, the return value
> when call is not supplied does not seem useful, although it is
> possible that it is correct in some technical sense.
>
>> match.call(definition=function(FirstArg, SecondArg)NULL,  
>> quote(anyFuncName(S=2, 1)))
> anyFuncName(FirstArg = 1, SecondArg = 2)
>> match.call(function(FirstArg, SecondArg)NULL,  
>> quote(anyFuncName(S=2, 1)))
> anyFuncName(FirstArg = 1, SecondArg = 2)
>> # without supplying 'call':
>> match.call(definition=function(FirstArg, SecondArg)NULL)
> Error in match.call(definition, call, expand.dots) :
>  unused argument (definition = function(FirstArg, SecondArg) NULL)
>> match.call(function(FirstArg, SecondArg)NULL)
> match.call(FirstArg = function(FirstArg, SecondArg) NULL)
>
>
>
>
>
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Tue, Jul 15, 2014 at 4:27 PM, David Winsemius <dwinsemius at comcast.net 
> > wrote:
>> The help page says:
>>
>> "Calling match.call outside a function without specifying  
>> definition is an
>> error."
>>
>> And yet when I send a function with a 'definition' argument it  
>> errors:
>>
>>> g
>> function(x, y=NULL, z=NULL) invisible(NULL)
>>> match.call(definition=g)
>> Error in match.call(definition, call, expand.dots) :
>>  unused argument(s) (definition = g)
>>
>> I wondered if this had something to do with primitive functions and  
>> their
>> ignoring names but:
>>
>>> is.primitive(match.call)
>> [1] FALSE
>>
>> Calling with an unnamed first argument succeeds:
>>
>>> match.call(g )
>> match.call(x = g)
>> --
>>
>> David Winsemius, MD
>> Alameda, CA, USA
>>
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>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
Alameda, CA, USA