78 lines
2.6 KiB
Python
Executable File
78 lines
2.6 KiB
Python
Executable File
# /usr/bin/env python3
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"""set_get_attr_example.py
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-----------------------
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This module contains a class named `Number` which implements special attribute
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access methods to demonstrate custom attribute setting and getting behaviors
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in a Python class.
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Here is a summary of its functionality and methods:
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- `__init__(self, number)`: Initializes a new instance with a `number` parameter.
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- `power(self)`: Squares the current value of the `_number` attribute. It utilizes
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`self.number` to access the `_number` attribute, which works correctly due to
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the overridden `__getattribute__` method.
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- `another_func(self)`: Prints a message when invoked.
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- `__str__(self)`: Returns a string representation of the `_number` attribute.
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The class also overrides special methods (`__setattr__`, `__getattribute__`,
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`__getattr__`) to define custom behaviors for setting, getting, and accessing
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non-existent attributes, respectively.
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Usage:
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If run as the main program, an instance of `Number` is created with an initial
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value of 5. The script then performs various operations to demonstrate the
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custom attribute access behaviors.
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Note:
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The `__getattribute__` method in the `Number` class is implemented such that if
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an attribute other than the ones listed in the `options` list is accessed, the
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`_number` attribute value is returned. This is demonstrated in the script where
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`number.num` and `number.number` (which are non-existing attributes) are accessed,
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but the `_number` value is printed instead of raising an AttributeError.
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"""
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class Number:
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def __init__(self, number):
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self._number = number
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def power(self):
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self._number = self.number * self.number
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def another_func(self):
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print("In another function")
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def __setattr__(self, name, value):
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# print(name, type(name), value, type(value))
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super().__setattr__("_number", 0)
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try:
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if isinstance(value, int):
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super().__setattr__("_number", value)
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elif isinstance(value, str):
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super().__setattr__("_number", int(value))
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except ValueError:
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return
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def __getattribute__(self, name):
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options = ["power", "another_func", "__class__"]
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if name in options:
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return super().__getattribute__(name)
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else:
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return super().__getattribute__("_number")
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def __str__(self):
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return str(self._number)
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def __getattr__(self, name):
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return self._number
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if __name__ == "__main__":
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number = Number(5)
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print(number.num)
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print(number.number)
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number.power()
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print(number.num)
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number.another_func()
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