New submission from George Sakkis <[email protected]>:
I'd like to propose two new optional boolean parameters to the @dataclass()
decorator, `asdict` and `astuple`, that if true, the respective methods are
generated as equivalent to the module-level namesake functions.
In addition to saving an extra imported name, the main benefit is performance.
By having access to the specific fields of the decorated class, it should be
possible to generate a more efficient implementation than the one in the
respective function. To illustrate the difference in performance, the asdict
method is 28 times faster than the function in the following PEP 557 example:
@dataclass
class InventoryItem:
'''Class for keeping track of an item in inventory.'''
name: str
unit_price: float
quantity_on_hand: int = 0
def asdict(self):
return {
'name': self.name,
'unit_price': self.unit_price,
'quantity_on_hand': self.quantity_on_hand,
}
In [4]: i = InventoryItem(name='widget', unit_price=3.0,
quantity_on_hand=10)
In [5]: asdict(i) == i.asdict()
Out[5]: True
In [6]: %timeit asdict(i)
5.45 µs ± 14.1 ns per loop (mean ± std. dev. of 7 runs, 100000 loops
each)
In [7]: %timeit i.asdict()
193 ns ± 0.443 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops
each)
Thoughts?
----------
components: Library (Lib)
messages: 340511
nosy: gsakkis
priority: normal
severity: normal
status: open
title: asdict/astuple Dataclass methods
type: enhancement
versions: Python 3.8
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Python tracker <[email protected]>
<https://bugs.python.org/issue36662>
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