Python 海象运算符( :=)的三种用法

my_list = [1,2,3]
count = len(my_list)
if count > 3:
   print(f"Error, {count} is too many items")

# when converting to walrus operator...
if (count := len(my_list)) > 3:
   print(f"Error, {count} is too many items")

line = f.readLine()
while line:
   print(line)
   line = f.readLine()
# when converting to walrus operator...while line := f.readLine():
   print(line)

n = 0
while n < 3:
   print(n) # 0,1,2
   n += 1
# when converting to walrus operator...
w = 0
while (w := w + 1) < 3:
   print(w) # 1,2

while True:
   p = input("Enter the passWord: ")
   if p == "the password":
      break
# when converting to walrus operator...
while (p := input("Enter the password: ")) != "the password":
   continue

scores = [22,54,75,89]
valid_scores = [
   longFunction(n)
   for n in scores
   if longFunction(n)
]

scores = [22,54,75,89]
valid_scores = [
   result for n in scores
   result := longFunction(n)
]

# look for failed inspections
# if there are failed inspections, assign to technicianrecords = api.readFailedRecords()
if len(records) > 0:
   for record in records:
      api.assignToTechnician(record)

if records := api.readFailedRecords():
   for record in records:
      api.assignToTechnician(record)