C-like structures in Python

Question

Is there a way to conveniently define a C-like structure in Python? I'm tired of writing stuff like:

class MyStruct():     def __init__(self, field1, field2, field3):         self.field1 = field1         self.field2 = field2         self.field3 = field3 

Answer 1

Update: Data Classes

With the introduction of Data Classes in Python 3.7 we get very close.

The following example is similar to the NamedTuple example below, but the resulting object is mutable and it allows for default values.

from dataclasses import dataclass   @dataclass class Point:     x: float     y: float     z: float = 0.0   p = Point(1.5, 2.5)  print(p)  # Point(x=1.5, y=2.5, z=0.0) 

This plays nicely with the new typing module in case you want to use more specific type annotations.

I've been waiting desperately for this! If you ask me, Data Classes and the new NamedTuple declaration, combined with the typing module are a godsend!

Improved NamedTuple declaration

Since Python 3.6 it became quite simple and beautiful (IMHO), as long as you can live with immutability.

A new way of declaring NamedTuples was introduced, which allows for type annotations as well:

from typing import NamedTuple   class User(NamedTuple):     name: str   class MyStruct(NamedTuple):     foo: str     bar: int     baz: list     qux: User   my_item = MyStruct('foo', 0, ['baz'], User('peter'))  print(my_item) # MyStruct(foo='foo', bar=0, baz=['baz'], qux=User(name='peter')) 

Answer 2

Use a named tuple, which was added to the collections module in the standard library in Python 2.6. It's also possible to use Raymond Hettinger's named tuple recipe if you need to support Python 2.4.

It's nice for your basic example, but also covers a bunch of edge cases you might run into later as well. Your fragment above would be written as:

from collections import namedtuple MyStruct = namedtuple("MyStruct", "field1 field2 field3") 

The newly created type can be used like this:

m = MyStruct("foo", "bar", "baz") 

You can also use named arguments:

m = MyStruct(field1="foo", field2="bar", field3="baz")