如何将Python字典的值映射到自定义函数参数并传入？

我定义了一个Python字典mpm_holidays：

mpm_holidays = {
    "New Year's Day (Observed)": (None, True),
    "Martin Luther King Jr. Day": ("art/MLKDay.png", True),
    "2022-02-14": ("art/ValentinesDay.png", False),
    "Good Friday": ("art/GoodFriday.png", True),
    "2022-04-16": ("art/GoodFriday.png", True),
    "Memorial Day": ("art/MemorialDay.png", True),
    "2022-05-28": (None, True),
    "2022-06-19": ("art/Juneteenth.png", False),
    "Independence Day": ("art/IndependenceDay.png", True),
    "Independence Day (Observed)": (None, True),
    "Labor Day": ("art/LaborDay.png", True),
    "2022-09-03": (None, True),
    "2022-09-05": (None, True),
    "Veterans Day": ("art/VeteransDay.png", True),
    "Veterans Day (Observed)": (None, True),
    "2022-10-31": ("art/Halloween.png", False),
    "Thanksgiving": ("art/Thanksgiving.png", True),
    "Day After Thanksgiving": (None, True),
    "Christmas Eve": ("art/ChristmasEve.png", True),
    "Christmas Eve (Observed)": (None, True),
    "Christmas Day": ("art/ChristmasDay.png", True),
    "New Year's Eve": ("art/NewYearsEve.png", True)
}

同时编写了函数overlays：

def overlays(art_to_use_, closure_):
    """ Imprint closure and/or holiday artwork. """
    if art_to_use_:
        calendarSheet.paste(
            Image.open(art_to_use_).convert("RGBA"),
            (0, 0),
            mask=Image.open(art_to_use_).convert("RGBA")
        )
    if closure_:
        calendarSheet.paste(
            Image.open(STATUS_CLOSED).convert("RGBA"),
            (0, 0),
            mask=Image.open(STATUS_CLOSED).convert("RGBA")
        )
    calendarSheet.save(calendarSheetFilename, format="png")

现在不清楚如何将字典的值映射到函数所需的参数，请问该如何实现？

你的字典每个值都是二元元组，正好和overlays函数的两个参数art_to_use_（元组第一个元素）、closure_（元组第二个元素）一一对应，直接用Python的元组解包语法就能实现映射，具体分两种场景：

1. 针对单个节日/日期处理 #

如果你想处理字典里的某一个特定条目，比如"Martin Luther King Jr. Day"，可以这样做：

# 获取对应的值元组
holiday_data = mpm_holidays["Martin Luther King Jr. Day"]
# 解包元组传入函数，等同于 overlays("art/MLKDay.png", True)
overlays(*holiday_data)

2. 遍历整个字典批量处理 #

如果需要处理字典里的所有条目，直接遍历字典的值即可：

for holiday_data in mpm_holidays.values():
    overlays(*holiday_data)

额外优化建议 #

注意你的函数里两次打开同一张图片（比如Image.open(art_to_use_)），可以优化成只打开一次，避免重复IO操作：

def overlays(art_to_use_, closure_):
    """ Imprint closure and/or holiday artwork. """
    if art_to_use_:
        img = Image.open(art_to_use_).convert("RGBA")
        calendarSheet.paste(img, (0, 0), mask=img)
    if closure_:
        closed_img = Image.open(STATUS_CLOSED).convert("RGBA")
        calendarSheet.paste(closed_img, (0, 0), mask=closed_img)
    calendarSheet.save(calendarSheetFilename, format="png")

内容的提问来源于stack exchange，提问作者stunafish