my_tibble <- function(data) {
    attr(data, "row.names") <- (1:lengths(data)[1])
    attr(data, "class") <- c("tbl_df", "tbl", "data.frame")
    return(data)
}

library(tibble)
my_tb <- my_tibble(list(x=1:3, y=letters[1:3]))
tb <- tibble(x=1:3 , y=letters[1:3])
identical(tb, my_tb)

my_factor <- function(data) {
    lvls <- unique(data)
    vec <- sapply(data, function(x) match(x, lvls), USE.NAMES=FALSE)
    attr(vec, "levels") <- lvls
    attr(vec, "class") <- "factor"
    return(vec)
}

my_fac <- my_factor (c("a", "b", "a", "a", "c", "c"))
fac <- factor(c("a", "b", "a", "a", "c", "c"))
identical(fac, my_fac)