
Why does x in "assign(x)" correctly evaluate to "rank" where
UseMethod(func) does not get correctly evaluated?

Can we use as.call(list(UseMethod,func))?

>> assign(paste(func,".default",sep=""),get(func),pos=env)
>>
>> assign(func,function(x,...) UseMethod(func),pos=env)

On Wed, Dec 22, 2010 at 9:03 PM, William Dunlap [via R]
<ml-node+3161542-1898476570-206552@n4.nabble.com> wrote:
> Try the following, which I haven't tested much
> and needs more error checking (e.g., to see that
> the function is not already generic and that
> its argument list is compatible with (x,...)).
> I put in the print statements to show what
> the calls to substitute() do.
>
> toGeneric <- function (funcName) {
>     stopifnot(is.character(funcName))
>     funcItself <- get(funcName)
>     stopifnot(is.function(funcItself))
>     envir <- environment(funcItself)
>     tmp <- substitute(funcSymbol <- function(x, ...)
> UseMethod(funcName),
>         list(funcSymbol = as.symbol(funcName), funcName = funcName))
>     print(tmp)
>     eval(tmp, envir = envir)
>     tmp <- substitute(defaultSymbol <- funcItself, list(defaultSymbol =
> as.symbol(paste(sep = ".",
>         funcName, "default")), funcItself = funcItself))
>     print(tmp)
>     eval(tmp, envir = envir)
> }
>
> E.g.,
>
>    > wsx <- function(x, base=2)log(x, base=base)
>    > toGeneric("wsx")
>    wsx <- function(x, ...) UseMethod("wsx")
>    wsx.default <- function (x, base = 2)
>    log(x, base = base)
>    > wsx
>    function (x, ...)
>    UseMethod("wsx")
>    > wsx.default
>    function (x, base = 2)
>    log(x, base = base)
>
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>> -----Original Message-----
>> From: [hidden email]
>> [mailto:[hidden email]] On Behalf Of rballen
>> Sent: Wednesday, December 22, 2010 2:42 PM
>> To: [hidden email]
>> Subject: [R] forcing evaluation of a char string argument
>>
>>
>> I'm trying to make a function to turn a regular function into
>> an S3 generic
>> one. I want myMethod to be:
>>
>> function(x,...) UseMethod("myMethod")
>>
>> But I keep getting:
>>
>> function(x,...) UseMethod(func)
>>
>> Here's the function:
>>
>> toGeneric<-function(func) {
>> env<-environment(get(func))
>>
>> # default method of new generic = the original function
>> assign(paste(func,".default",sep=""),get(func),pos=env)
>>
>> assign(func,function(x,...) UseMethod(func),pos=env)
>> }
>>
>> toGeneric("myMethod")
>>
>> I messed around with force, substitute, and deparse, but I
>> can't get any of
>> those to help.
>>
>> Thanks.
>> --
>> View this message in context:
>> http://r.789695.n4.nabble.com/forcing-evaluation-of-a-char-str
> ing-argument-tp3161365p3161365.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
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>
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