python 嵌套型partials的使用

from functools import partial
def func1(f):
    return f
def func2(f1):
    return f1
def func(n):
    return n

p = partial(func2, partial(func1, partial(func, 5)))
print(p()()())
# 输出5

p()
# 输出5

def date_trunc(time_unit: str, field):
    return f'date_trunc("{time_unit}", `{field}`)'


print(date_trunc("WEEK", "event_date"))
print(date_trunc("DAY", "event_date"))
...

from enum import Enum
from functools import partial


def date_trunc(time_unit: str, field):    # 注意这里的date_trunc和上面简略版举例的有所不同，需要两个参数
    return  f'date_trunc("{time_unit}", `{field}`)'


class TimeFormatter(Enum):
    DAY = partial(date_trunc, "DAY")
    WEEK = partial(date_trunc, "WEEK")
    MONTH = partial(date_trunc, "MONTH")

    def __call__(self, *args, **kwargs):
        return self.value(*args, **kwargs)

field = "event_time"
tf_wk = TimeFormatter.__getattr__("WEEK")    # 先校验格式
print(tf_wk(field))        # 传入相应的field对象就会执行对应的date_trunc方法截断时间
tf_day = TimeFormatter.__getattr__("DAY")    # 校验格式
print(tf_day(field))    # 执行date_trunc

from_timestamp(date_trunc("DAY", `event_time`), "yyyy-MM-dd")

from enum import Enum
from functools import partial


def from_timestamp(field, time_fmt: str):
    return f'from_timestamp(`{field}`, "{time_fmt}")'


class TimeFormatter(Enum):
    HOUR = partial(from_timestamp, partial(date_trunc, "HOUR"))

    def __call__(self, *args, **kwargs):
        return self.value(*args, **kwargs)


tf_hour = TimeFormatter.__getattr__("HOUR")
print(tf_hour("event_hour"))

from enum import Enum
from functools import partial


def date_trunc(time_unit: str, field):
    return f'date_trunc("{time_unit}", `{field}`)'


def from_timestamp(field, time_fmt: str):
    return f'from_timestamp(`{field}`, "{time_fmt}")'


def fts(time_fmt, time_unit, field):
    return from_timestamp(date_trunc(time_unit, field), time_fmt)


class TimeFormatter2(Enum):
    month = partial(fts, "yyyy-MM", "month")

    def __call__(self, *args, **kwargs):
        return self.value(*args, **kwargs)

def nested_partials(f2, f1, n):
    return f2(f1(n))


p = partial(nested_partials, func2, func1)
print(p(5))