需要一些帮助定义一些方法

Question

如果我可以得到一些关于打印出用户输入的数据的分配问题的帮助，我将非常感激（在这个具体的例子中，年，模型和使汽车的）：

# DEFINE YOUR CAR CLASS HERE 

# create empty array 
array_of_cars = Array.new 

# prompt for and get number of cars 
print "How many cars do you want to create? " 
num_cars = gets.to_i 

# create that many cars 
for i in 1..num_cars 
# get the make, model, and year 
puts 
print "Enter make for car #{i}: " 
make = gets.chomp 

print "Enter model for car #{i}: " 
model = gets.chomp 

print "Enter year of car #{i}: " 
year = gets.to_i 

# create a new Car object 
c = Car.new 

# set the make, model, and year 
# that we just read in 
c.set_make(make) 
c.set_model(model) 
c.set_year(year) 

# add the Car object to the array 
array_of_cars << c 
end 

# print out the information for 
# the Car objects in the array 
puts 
puts "You have the following cars: " 

for car in array_of_cars 
puts "#{car.get_year} #{car.get_make} #{car.get_model}" 
end 

我已经有程序的某些部分，但它的主要部分挣扎，因为我那种知道该怎么做，但不是如何实现它。

因此，对于这部分：＃定义你的车类HERE

我得到这个：

class Car 

def assign(m,n,y) 
    #instance variables 
    @make = m 
    @model = n 
    @year = y 
end 
    #instance methods 
def set_make 

end 

def set_model 

end 

def set_year 

end 

def get_make 

end 

def get_model 

end 

def get_year 

end 

首先，我才这样做的权利与实例变量？

然后，“设置”的目的是将值保存到数组中吗？然后“get”让我稍后提取它们。我想我会理解这个概念，如果有人能告诉我如何定义其中的一个。

我知道这看起来有点含糊，所以我会尽力澄清是否有问题发生。也很抱歉的文字墙，谢谢你！

Answer 1

首先，在“惯用的红宝石”我们所说的getter和setter @variable为variable（吸气）和variable=（二传）构造函数将被命名为initialize，不assign。

有一个帮手，同时定义为引擎盖下的声明getter和setter方法，让你的类定义可能是短类，Module#attr_accessor：

class Car 
    attr_accessor :make, :model, :year 

    def initialize(make, model, year) 
    @make = make 
    @model = model 
    @year = year 
    end 
end 

到目前为止好。你的代码的其余部分将是：

array_of_cars = [] # use Array.new with parameter, [] otherwise 

# prompt for and get number of cars 
print "How many cars do you want to create? " 
num_cars = gets.to_i 

# create that many cars 
(1..num_cars).each do |i| # in idiomatic ruby, never use for loops 
    # get the make, model, and year 
    puts "Enter make for car #{i}: " 
    make = gets.chomp 

    print "Enter model for car #{i}: " 
    model = gets.chomp 

    print "Enter year of car #{i}: " 
    year = gets.to_i 

    # create a new Car object 
    c = Car.new(make, model, year) 

    # add the Car object to the array 
    array_of_cars << c 
end 

# print out the information for 
# the Car objects in the array 
puts 
puts "You have the following cars: " 

array_of_cars.each do |car| 
    puts "#{car.year} #{car.make} #{car.model}" 
end 

BTW，而不是预先创建一个数组，一个可以更好地使用Enumerable#map：

# prompt for and get number of cars 
print "How many cars do you want to create? " 
num_cars = gets.to_i 

# ⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓ DECLARE IT IN-PLACE 
array_of_cars = (1..num_cars).map do |i| 
    puts "Enter make for car #{i}: " 
    make = gets.chomp 

    print "Enter model for car #{i}: " 
    model = gets.chomp 

    print "Enter year of car #{i}: " 
    year = gets.to_i 

    # create a new Car object 
    Car.new(make, model, year) 
end 

这将产生需要开箱的数组。

---

附录：定义getter和setter手动：

class Car 
    attr_accessor :make, :model 

    def initialize(make, model, year) 
    @make = make 
    @model = model 
    @year = year 
    end 

    # manually declare getter for year: 
    def year 
    @year 
    end 
    # manually declare setter for year: 
    def year=(year) 
    @year = year 
    end 
end