Let’s confirm that this two-class setup really made Repeater objects compatible with for-in loop iteration.
#Python izip example code
We’ll take a closer look at these two methods and how they work together after some hands-on experimentation with the code we’ve got so far. The two dunder methods we defined, _iter_ and _next_, are the key to making a Python object iterable. In this code example, Repeater and RepeaterIterator are working together to support Python’s iterator protocol.
In RepeaterIterator._next_, we reach back into the “source” Repeater instance and return the value associated with it.
That way we can hold on to the “source” object that’s being iterated over. In the _init_ method we link each RepeaterIterator instance to the Repeater object that created it. valueĪgain, RepeaterIterator looks like a straightforward Python class, but you might want to take note of the following two things: source = source def _next_ ( self ): return self. Over the next few paragraphs we’re going to implement a class called Repeater that can be iterated over with a for-in loop, like so:Ĭlass RepeaterIterator : def _init_ ( self, source ): self. I think doing it this way gives you a more applicable understanding of how iterators work in Python. The example I’m using here might look different from the examples you’ve seen in other iterator tutorials, but bear with me. We’ll begin by writing a class that demonstrates the bare-bones iterator protocol in Python. Ready? Let’s jump right in! Python Iterators That Iterate Forever And at the end of this tutorial we’ll go over some differences that exist between Python 2 and 3 when it comes to iterators. I’ll tie each example back to the for-in loop question we started out with.
We’ll focus on the core mechanics of iterators in Python 3 first and leave out any unnecessary complications, so you can see clearly how iterators behave at the fundamental level. They’ll serve as “non-magical” examples and test implementations you can build upon and deepen your understanding with.
#Python izip example how to
In this tutorial you’ll see how to write several Python classes that support the iterator protocol. Just like decorators, iterators and their related techniques can appear quite arcane and complicated on first glance. Objects that support the _iter_ and _next_ dunder methods automatically work with for-in loops.īut let’s take things step by step. You’ll find the answer to these questions in Python’s iterator protocol: Numbers = for n in numbers : print ( n )īut how do Python’s elegant loop constructs work behind the scenes? How does the loop fetch individual elements from the object it is looping over? And how can you support the same programming style in your own Python objects?
0 kommentar(er)
