Genéricos e métodos

Programação Orientada a Objetos com S3 e R6 em R

Richie Cotton

Data Evangelist at DataCamp

summary(c(TRUE, FALSE, NA, TRUE))

   Mode   FALSE    TRUE    NA's 
logical       1       2       1

summary(rgamma(1000, 1))

    Min.  1st Qu.   Median     Mean  3rd Qu.     Max. 
0.000354 0.276500 0.690300 1.020000 1.384000 9.664000

function overloading = comportamento

dependente da entrada

ch2_1-generics-and-methods.007.png

ch2_1-generics-and-methods.008.png

ch2_1-generics-and-methods.009.png

ch2_1-generics-and-methods.010.png

print

function (x, ...) 
UseMethod("print")
<bytecode: 0x1062f0870>
<environment: namespace:base>

Métodos são nomeados generic.class

print.Date
summary.factor
unique.array

Assinaturas de métodos contêm as da genérica

args(print)

function (x, ...) 
NULL

args(print.Date)

function (x, max = NULL, ...) 
NULL

passe argumentos entre métodos com `...`

inclua-o tanto na genérica quanto nos métodos

print.function

function (x, useSource = TRUE, ...) 
.Internal(print.function(x, useSource, ...))

print.Date

function (x, max = NULL, ...) 
{
    if (is.null(max)) 
        max <- getOption("max.print", 9999L)
    if (max < length(x)) {
        print(format(x[seq_len(max)]), max = max, ...)
        cat(" [ reached getOption(\"max.print\") -- omitted", 
            length(x) - max, "entries ]\n")
    }
    else print(format(x), max = max, ...)
    invisible(x)
}