Home  >  Article  >  Backend Development  >  How Can I Bind Unbound Methods in Python Without Triggering Invocation?

How Can I Bind Unbound Methods in Python Without Triggering Invocation?

Mary-Kate Olsen
Mary-Kate OlsenOriginal
2024-11-02 11:26:02809browse

How Can I Bind Unbound Methods in Python Without Triggering Invocation?

Binding Unbound Methods Without Invocation

In Python, defining a class-level list of tuples where each tuple represents a button and its corresponding event handler can enhance data organization. However, binding unbound methods to an instance without triggering their execution can pose a challenge.

The issue arises when the event handler values are unbound methods, leading to runtime errors. While functools.partial offers a workaround, a more Pythonic approach is to exploit the descriptor behavior of functions.

Descriptors, including functions, have an __get__ method that, when called, binds the function to an instance. Utilizing this method, we can bind unbound methods as follows:

<code class="python">bound_handler = handler.__get__(self, MyWidget)</code>

This technique effectively binds the unbound method handler to the MyWidget instance without calling it.

Alternatively, a reusable function can encapsulate this binding logic:

<code class="python">def bind(instance, func, as_name=None):
    """
    Bind the function *func* to *instance*, with either provided name *as_name*
    or the existing name of *func*. The provided *func* should accept the 
    instance as the first argument, i.e. "self".
    """
    if as_name is None:
        as_name = func.__name__
    bound_method = func.__get__(instance, instance.__class__)
    setattr(instance, as_name, bound_method)
    return bound_method</code>

This function allows flexible binding with custom names:

<code class="python">something = Thing(21)

def double(self):
    return 2 * self.val

bind(something, double)
something.double()  # returns 42</code>

The above is the detailed content of How Can I Bind Unbound Methods in Python Without Triggering Invocation?. For more information, please follow other related articles on the PHP Chinese website!

Statement:
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn