Demo of the @patch_to decorator from fastcore

demo.py

from fastcore.basics import patch_to


class Demo:
    val = 10
    def __init__(self, val):
        self.val = val
    
# ====================
# The default mode
# ====================
@patch_to(Demo)
def print(self):
    print(self.val)
    
Demo(5).print() # prints 5
    
# =======================
# The class method mode
# =======================
@patch_to(Demo, cls_method=True)
def print(self):
    print(self.val)
    
Demo(5).print() # prints 10

# =====================
# The property mode
# =====================
@patch_to(Demo, as_prop=True)
def print(self):
    print(self.val)
    
Demo(5).print # prints 5

# =====================
# Addition notes
# =====================
#
# The function under @patch_to doesn't overwrite existing functions.
# In this example, the global `print` built-in function still works normally:

print("I am a print statement.") # prints I am a print statement.