classMethods.R: list all generic functions for a given class

classMethods.R

classMethods <- function(cl) {
    if(!is.character(cl)) {
        cl<-class(cl)
    }
    ml<-lapply(cl, function(x) {
        sname <- gsub("([.[])", "\\\\\\1", paste0(".", x, "$"))
        m <- methods(class=x)
        if(length(m)) {
            data.frame(
                m=as.vector(m), 
                c=x, n=sub(sname, "", as.vector(m)),
                attr(m,"info"),
                stringsAsFactors=F
            ) 
        } else {
            NULL
        }
    })
    df<-do.call(rbind, ml)
    df<-df[!duplicated(df$n),]
    structure(df$m, 
        info=data.frame(visible=df$visible, from=df$from), 
        class="MethodsFunction")
}

test.classMethods.R

g <- glm(y~x,data=data.frame(x=1:10,y=1:10))
classMethods(g)
classMethods(c("glm","lm"))