搜尋
即使沒有迭代,next
函式也很有用。將生成器表示式傳遞給 next
是一種快速搜尋匹配某個謂詞的元素的第一次出現的方法。程式程式碼就好
def find_and_transform(sequence, predicate, func):
for element in sequence:
if predicate(element):
return func(element)
raise ValueError
item = find_and_transform(my_sequence, my_predicate, my_func)
可以替換為:
item = next(my_func(x) for x in my_sequence if my_predicate(x))
# StopIteration will be raised if there are no matches; this exception can
# be caught and transformed, if desired.
為此,可能需要建立別名(如 first = next
)或包裝函式來轉換異常:
def first(generator):
try:
return next(generator)
except StopIteration:
raise ValueError