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Unbinding the Gordian Knot: Binding Unbound Methods Seamlessly
In Python, binding unbound methods without invoking them can present a coding challenge. Consider this scenario:
<code class="python">class MyWidget(wx.Window): buttons = [("OK", OnOK), ("Cancel", OnCancel)] def setup(self): for text, handler in MyWidget.buttons: b = wx.Button(parent, label=text).bind(wx.EVT_BUTTON, handler)</code>
Here, handler represents an unbound method, leading to runtime errors. While functools.partial offers a workaround, Python's innate descriptor capabilities provide an elegant solution.
Unveiling the Power of Descriptors
All functions in Python possess intrinsic descriptor properties. By leveraging their __get__ method, unbound methods can be bound to an instance:
<code class="python">bound_handler = handler.__get__(self, MyWidget)</code>
This technique enables binding of unbound methods without triggering their execution.
A Comprehensive Example
To illustrate, let's implement a custom bind function:
<code class="python">def bind(instance, func, as_name=None): 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>
Utilizing this bind function, we can achieve the desired functionality:
<code class="python">class Thing: def __init__(self, val): self.val = val something = Thing(21) def double(self): return 2 * self.val bind(something, double) something.double() # returns 42</code>
By embracing the power of descriptors, we effortlessly bind unbound methods, unlocking a myriad of coding possibilities without compromising on Pythonic principles.
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