How to Create a Custom String Representation for a Class Object

How to create a custom string representation for a class object?

Implement __str__() or __repr__() in the class's metaclass.

class MC(type):
  def __repr__(self):
    return 'Wahaha!'

class C(object):
  __metaclass__ = MC

print(C)

Use __str__ if you mean a readable stringification, use __repr__ for unambiguous representations.

Custom String representation of an Object in Java

You need to override the toString() method.

@Override
public String toString() {
    return "Empty JLabel";
}

How to make the Python str() function work with a custom class?

def __str__(self): will be used when you try to str(my_object). It would also be called in string interpolation such as f'This is my object: {my_object}'

def __repr__(self): will be used to represent your object in a console

>>> class A():
...     def __str__(self):
...             return 'im a string nicely formatted'
...     def __repr__(self):
...             return 'class A object'
...
>>> a = A()
>>> print(a)
im a string nicely formatted
>>> a
class A object

How to customise the string representation of an object while debugging Python in VS Code

This can be done by overriding the __repr__() method of the object.

class Person(object):
    def __init__(self, name: str, age: int) -> None:
        self.name = name
        self.age = age

    def __repr__(self) -> str:
        return f"Person({self.name=}, {self.age=})"

The __repr__() method is used by VS Code's debugger rather than the __str__() method, since __str__() is intended for user-facing representation and __repr__() is intended for debugging.

How do I change the string representation of a Python class?

The closest equivalent to Java's toString is to implement __str__ for your class. Put this in your class definition:

def __str__(self):
     return "foo"

You may also want to implement __repr__ to aid in debugging.

See here for more information:

• Special Method Names - Basic Customization

Change the string representation of a class itself

You need to use meta classes:

class Meta(type):
    def __repr__(self):
        return "hi"

class Test(metaclass=Meta):
    pass

print(Test)
>>> hi

The __repr__ method works on instances not on classes. However in python a class is itself an "instance" of a meta class type. So if you make a custom meta class with a custom __repr__ method, all classes that are created with your meta class will use your __repr__ method.

Some more reading on meta classes.

String representation of a class in Python 3

What changed is how the metaclass is declared in 3.x.

class C(metaclass=MC):
    pass

Swift - How to I define a special method for my class that returns a string representation of its object

Just conform to the CustomStringConvertible protocol. All you have to do is implement the description property.

struct Person: CustomStringConvertible {
    let name: String
    let age: Int

    var description: String {
        return "[name: \(name), age: \(age)]"
    }
}

print(Person(name: "bob", age: 32)) // [name: bob, age: 32]

Custom 'String' Class

Implement a toString method.

toString is a method on Object, so every java object inherits one. The default implementation that you inherit is only useful for getting the class type, and for distinguishing one object from another; the format is: ClassName@HashCode. There are no details unique to your implementation.

In your own classes, to get the description that you want you'll need to override the toString method, so that in contexts where a String is expected, e.g. when you call System.out.println(myObject.toString());, your own format is used.

It's often a good idea to do this, for a more readable description of your object. You can always call super.toString to include the output from the default - ClassName@HashCode - in your own output.

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