I'm trying to learn python and I now I am trying to get the hang of classes and how to manipulate them with instances.
I can't seem to understand this practice problem:
Create and return a student object whose name, age, and major are the same as those given as input
def make_student(name, age, major)
I just don't get what it means by object, do they mean I should create an array inside the function that holds these values? or create a class and let this function be inside it, and assign instances? (before this question i was asked to set up a student class with name, age, and major inside)
class Student:
name = "Unknown name"
age = 0
major = "Unknown major"
This question is related to
python
when you create an object using predefine class, at first you want to create a variable for storing that object. Then you can create object and store variable that you created.
class Student:
def __init__(self):
# creating an object....
student1=Student()
Actually this init method is the constructor of class.you can initialize that method using some attributes.. In that point , when you creating an object , you will have to pass some values for particular attributes..
class Student:
def __init__(self,name,age):
self.name=value
self.age=value
# creating an object.......
student2=Student("smith",25)
Create a class and give it an __init__
method:
class Student:
def __init__(self, name, age, major):
self.name = name
self.age = age
self.major = major
def is_old(self):
return self.age > 100
Now, you can initialize an instance of the Student
class:
>>> s = Student('John', 88, None)
>>> s.name
'John'
>>> s.age
88
Although I'm not sure why you need a make_student
student function if it does the same thing as Student.__init__
.
Objects are instances of classes. Classes are just the blueprints for objects. So given your class definition -
# Note the added (object) - this is the preferred way of creating new classes
class Student(object):
name = "Unknown name"
age = 0
major = "Unknown major"
You can create a make_student
function by explicitly assigning the attributes to a new instance of Student
-
def make_student(name, age, major):
student = Student()
student.name = name
student.age = age
student.major = major
return student
But it probably makes more sense to do this in a constructor (__init__
) -
class Student(object):
def __init__(self, name="Unknown name", age=0, major="Unknown major"):
self.name = name
self.age = age
self.major = major
The constructor is called when you use Student()
. It will take the arguments defined in the __init__
method. The constructor signature would now essentially be Student(name, age, major)
.
If you use that, then a make_student
function is trivial (and superfluous) -
def make_student(name, age, major):
return Student(name, age, major)
For fun, here is an example of how to create a make_student
function without defining a class. Please do not try this at home.
def make_student(name, age, major):
return type('Student', (object,),
{'name': name, 'age': age, 'major': major})()
Source: Stackoverflow.com