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element_immutable.py
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52 lines (40 loc) · 1.35 KB
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class Element:
__slots__ = (
'name',
'number',
'symbol',
'__weakref__',
)
def __init__(self, symbol, number, name):
self.symbol = symbol.title()
self.number = number
self.name = name.lower()
def __repr__(self):
return f"{self.symbol} ({self.name}): {self.number}"
def __str__(self):
return self.symbol
def __hash__(self):
return hash(self.symbol)
def __eq__(self, other):
return self.symbol == other.symbol
def __lt__(self, other):
return self.symbol < other.symbol
def __le__(self, other):
return self.symbol <= other.symbol
def __selfattr__(self, name, value):
if hasattr(self, name):
raise AttributeError(
f"'{type(self)}' object attribute '{name}' is read-only"
)
object.__setattr__(self, name, value)
def __delattr__(self, name):
raise AttributeError(
f"'{type(self)}' object attribute '{name}' is read-only"
)
oxygen = Element('O', 8, 'oxygen')
iron = Element('Fe', 26, 'iron')
print(oxygen) # prints 'O (Oxygen): 8'
print(f"{iron!r}") # prints 'Fe (Iron): 26'
iron.atomic_mass = 55.845 # raises AttributeError
iron.symbol = "Ir" # raises AttributeError
del iron.symbol # raises AttributeError