> ?UseMethod()
> whoAmI.foo <- function(x) print("I am a foo")
>
> whoAmI.bar <- function(x) print("I am a bar")
> whoAmI.default <- function(x) print("I don't know who I am")
> a = 1:10
>
> b = 2:20
>
> whoAmI(a)
[1] "I don't know who I am"
> attr(a,'class') <- 'foo'
> class(a)
[1] "foo"
> a
[1] 1 2 3 4 5 6 7 8 9 10
attr(,"class")
[1] "foo"
> attr(b,'class')<-c('baz','bam','bar')
> b
[1] 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
attr(,"class")
[1] "baz" "bam" "bar"
> class(b)
[1] "baz" "bam" "bar"
> whoAmI(a)
[1] "I am a foo"
> whoAmI(b)
[1] "I am a bar"
> a
[1] 1 2 3 4 5 6 7 8 9 10
attr(,"class")
[1] "foo"
> attr(a,'class') <- 'bar'
> whoAmI(a)
[1] "I am a bar"
> meth1 <- function(x) UseMethod("meth1")
>
> whoAmI(a,b)
Error in whoAmI.bar(a, b) : unused argument (b)
> whoAmI(a)
[1] "I am a bar"
> whoAmI(a,b)
Error in whoAmI.bar(a, b) : unused argument (b)
> dd<-1:100
> dd
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
[20] 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
[39] 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57
[58] 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
[77] 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
[96] 96 97 98 99 100
> dd<-1:100，dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
