my_vector <- 1:5

my_lm <- lm(mpg ~ hp, data = mtcars)

my_df <- mtcars

print(my_vector)

print(my_lm)

print(my_df)

summary(my_vector)

summary(my_lm)

summary(my_df)

summary <- function(x) {
  if (is.numeric(x)) {
    # ...
  } else if (is.lm(x)) {
    # ...
  } else if (is.df(x)) {
    # ...
  }
  # ...
}

human <- function(name, dob) {
  output <- list(
    name = name,
    dob = dob
  )
  class(output) <- "human"
  output
}

alice <- human(name = "Alice", dob = as.Date("1980-04-10"))

alicehuman <- function(name, dob) {
  output <- list(
    name = name,
    dob = dob
  )
  class(output) <- "human"
  output
}

alice <- human(name = "Alice", dob = as.Date("1980-04-10"))

alicehuman <- function(name, dob) {
  output <- list(
    name = name,
    dob = dob
  )
  class(output) <- "human"
  output
}

alice <- human(name = "Alice", dob = as.Date("1980-04-10"))

alicehuman <- function(name, dob) {
  output <- list(
    name = name,
    dob = dob
  )
  class(output) <- "human"
  output
}

alice <- human(name = "Alice", dob = as.Date("1980-04-10"))

alicehuman <- function(name, dob) {
  output <- list(
    name = name,
    dob = dob
  )
  class(output) <- "human"
  output
}

alice <- human(name = "Alice", dob = as.Date("1980-04-10"))

alicehuman <- function(name, dob) {
  output <- list(
    name = name,
    dob = dob
  )
  class(output) <- "human"
  output
}

alice <- human(name = "Alice", dob = as.Date("1980-04-10"))

alice

print.human <- function(h) {
  age <- (as.Date(Sys.time()) - h$dob) / 365
  cat("A human called", h$name, "who is", age, "years old")
}

print(alice)

# Generic
introduce <- function(x, ...) {
  UseMethod("introduce")
}

# Method
introduce.human <- function(h) {
  cat("Hello, my name is", h$name)
}


introduce(alice)# Generic
introduce <- function(x, ...) {
  UseMethod("introduce")
}

# Method
introduce.human <- function(h) {
  cat("Hello, my name is", h$name)
}


introduce(alice)# Generic
introduce <- function(x, ...) {
  UseMethod("introduce")
}

# Method
introduce.human <- function(h) {
  cat("Hello, my name is", h$name)
}


introduce(alice)# Generic
introduce <- function(x, ...) {
  UseMethod("introduce")
}

# Method
introduce.human <- function(h) {
  cat("Hello, my name is", h$name)
}


introduce(alice)

r_user <- function(name, dob, favourite_package) {
  output <- list(
    name = name,
    dob = dob,
    favourite_package = favourite_package
  )
  class(output) <- c("ruser", "human")
  output
}

bob <- r_user(name = "Bob",
              dob = as.Date("1985-10-13"),
              favourite_package = "ggplot2")

class(bob)

introduce.ruser <- function(r) {
  cat("Hello, my name is",
      r$name,
      "and I'm a big fan of",
      r$favourite_package)
}

introduce(bob)

class(bob) <- "lm"

print(bob)

setClass(
  "Human",
  slots = c(
    name = "character",
    dob = "Date"
  )
)setClass(
  "Human",
  slots = c(
    name = "character",
    dob = "Date"
  )
)setClass(
  "Human",
  slots = c(
    name = "character",
    dob = "Date"
  )
)setClass(
  "Human",
  slots = c(
    name = "character",
    dob = "Date"
  )
)setClass(
  "Human",
  slots = c(
    name = "character",
    dob = "Date"
  )
)setClass(
  "Human",
  slots = c(
    name = "character",
    dob = "Date"
  )
)

alice <- new("Human", name = "Alice", dob = 123)

alice@name

setGeneric("name", function(x) standardGeneric("name"))

setGeneric("name<-", function(x, value) standardGeneric("name<-"))

setMethod("name", "Human", function(x) x@name)
setMethod("name<-", "Human", function(x, value) {
  x@name <- value
  x
})

name(alice)

name(alice) <- "Alice Bloggs"
name(alice)

setGeneric("favPackage", function(x) standardGeneric("favPackage"))

setMethod("favPackage", "Ruser", function(x) x@favourite_package)

setClass(
  "Ruser",
  contains = "Human",
  slots = c(
    favourite_package = "character"
  )
)

bob <- new(
  "Ruser",
  name = "Bob",
  dob = as.Date("1985-10-13"),
  favourite_package = "ggplot2")

bob

setGeneric(
  "Meets",
  function(x, y) standardGeneric("Meets"),
  signature = c("x", "y")
)setGeneric(
  "Meets",
  function(x, y) standardGeneric("Meets"),
  signature = c("x", "y")
)setGeneric(
  "Meets",
  function(x, y) standardGeneric("Meets"),
  signature = c("x", "y")
)

setMethod(
  "Meets",
  signature = c("Human", "Human"),
  function(x, y) {
    cat(name(x), "says hello to", name(y))
  })

Meets(alice, bob)setMethod(
  "Meets",
  signature = c("Human", "Human"),
  function(x, y) {
    cat(name(x), "says hello to", name(y))
  })

Meets(alice, bob)setMethod(
  "Meets",
  signature = c("Human", "Human"),
  function(x, y) {
    cat(name(x), "says hello to", name(y))
  })

Meets(alice, bob)

setMethod(
  "Meets",
  signature = c("Ruser", "Human"),
  function(x, y) {
    cat(name(x), "says hello to",
        name(y), "and tries not to talk about",
        favPackage(x))
  }
)

Meets(bob, alice)

setMethod(
  "Meets",
  signature = c("Ruser", "Ruser"),
  function(x, y) {
    cat(name(x), "tells",
        name(y), "all about",
        favPackage(x))
  }
)

charlie <- new("Ruser", name = "Charlie",
               dob = as.Date("1990-03-05"),
               favourite_package = "dplyr")

Meets(bob, charlie)

methods("Meets")

cat(paste(methods("Meets"), collapse = "\n"))

library(R7)

human <- new_class(
  "human",
  properties = list(
    name = class_character,
    dob = class_Date
  )
)

alice <- human(
  name = "alice",
  dob = as.Date("1980-04-10"))

alicehuman <- new_class(
  "human",
  properties = list(
    name = class_character,
    dob = class_Date
  )
)

alice <- human(
  name = "alice",
  dob = as.Date("1980-04-10"))

alicehuman <- new_class(
  "human",
  properties = list(
    name = class_character,
    dob = class_Date
  )
)

alice <- human(
  name = "alice",
  dob = as.Date("1980-04-10"))

alicehuman <- new_class(
  "human",
  properties = list(
    name = class_character,
    dob = class_Date
  )
)

alice <- human(
  name = "alice",
  dob = as.Date("1980-04-10"))

alice

alice@name

introduce <- new_generic(
  "introduce",
  "x"
  )

method(introduce, human) <-
  function(x) {
    cat("Hello, I'm", x@name)
  }

introduce(alice)introduce <- new_generic(
  "introduce",
  "x"
  )

method(introduce, human) <-
  function(x) {
    cat("Hello, I'm", x@name)
  }

introduce(alice)introduce <- new_generic(
  "introduce",
  "x"
  )

method(introduce, human) <-
  function(x) {
    cat("Hello, I'm", x@name)
  }

introduce(alice)introduce <- new_generic(
  "introduce",
  "x"
  )

method(introduce, human) <-
  function(x) {
    cat("Hello, I'm", x@name)
  }

introduce(alice)

r_user <- new_class(
  "ruser",
  parent = human,
  properties = list(
    favourite_package = class_character
  )
)

bob <- r_user(
  name = "Bob",
  dob = as.Date("1985-10-13"),
  favourite_package = "ggplot2"
)r_user <- new_class(
  "ruser",
  parent = human,
  properties = list(
    favourite_package = class_character
  )
)

bob <- r_user(
  name = "Bob",
  dob = as.Date("1985-10-13"),
  favourite_package = "ggplot2"
)r_user <- new_class(
  "ruser",
  parent = human,
  properties = list(
    favourite_package = class_character
  )
)

bob <- r_user(
  name = "Bob",
  dob = as.Date("1985-10-13"),
  favourite_package = "ggplot2"
)

meets <- new_generic(
  "meets",
  c("x", "y")
)

method(meets,
       list(human, human)) <- 
  function(x, y) {cat(x@name, "greets", y@name)}

method(meets,
       list(r_user, r_user)) <-
  function(x, y) {cat(x@name, "tells",
                      y@name, "all about",
                      x@favourite_package)}meets <- new_generic(
  "meets",
  c("x", "y")
)

method(meets,
       list(human, human)) <- 
  function(x, y) {cat(x@name, "greets", y@name)}

method(meets,
       list(r_user, r_user)) <-
  function(x, y) {cat(x@name, "tells",
                      y@name, "all about",
                      x@favourite_package)}meets <- new_generic(
  "meets",
  c("x", "y")
)

method(meets,
       list(human, human)) <- 
  function(x, y) {cat(x@name, "greets", y@name)}

method(meets,
       list(r_user, r_user)) <-
  function(x, y) {cat(x@name, "tells",
                      y@name, "all about",
                      x@favourite_package)}

meets(alice, alice)

meets(alice, bob)

meets(bob, alice)

meets(bob, bob)