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Python - Enum Class

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• Python - Enum Class
  • Enum class
  • Create and Access to Enum Class
  • Loop Enum
  • List an Enum
  • Enum’s Size: len()
  • Compare Enum Memebers

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Enum class

• Enum is the class in Python used for developing the enumerations.
  • 通常用于创建常量, 因为 Python 没有常量.

• Enumeration is the set of symbolic members or names which are bounded to the constant and unique values.

  • The members of the enumeration can be equated by using these symbolic names.
  • The enumeration can be repeated by itself over them.

• The members of the Enum class are called Enumeration, and also hashable.

  • Therefore, these members can be used for sets and dictionaries.
• The characteristics of the Enum class are:
  • The users can check the types of Enum by using the type() method.
  • By using the ‘name’ keyword, the users can display the name of the Enum.
  • The Enum is the evaluable string representation of the object known as repr().

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Create and Access to Enum Class

• import enum file
• using inheritance class enum_name(enum.Enum):

import enum
# we will use enum class for creating enumerations


class Weekdays(enum.Enum):
    Sunday = 1
    Monday = 2
    Tuesday = 3
    Wednesday = 4
    Thursday = 5
    Friday = 6
    Saturday = 7


# print the enum member as the string
print(Weekdays.Wednesday)           # Weekdays.Wednesday

# check the type of enum member
print(type(Weekdays.Wednesday))     # <enum 'Weekdays'>

# access member by name
print(Weekdays["Wednesday"])        # Weekdays.Wednesday
# access member by value
print(Weekdays(4))                  # Weekdays.Wednesday

# print the enum member as a repr object
print(repr(Weekdays.Wednesday))     # <Weekdays.Wednesday: 4>

# print name of enum member
print(Weekdays.Wednesday.name)      # Wednesday
print(Weekdays.Wednesday.value)     # 4

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Loop Enum

# loop an enum object
for weekday in Weekdays:
    print(weekday)
# Weekdays.Sunday
# Weekdays.Monday
# Weekdays.Tuesday
# Weekdays.Wednesday
# Weekdays.Thursday
# Weekdays.Friday
# Weekdays.Saturday

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List an Enum

# list all members
print(list(Days))
# [<Days.Sunday: 1>, <Days.Monday: 2>, <Days.Wednesday: 4>, <Days.Thursday: 5>, <Days.Saturday: 7>]

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Enum’s Size: len()

# get enum class's size
print(len(Weekdays))    # 7

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Compare Enum Memebers

import enum
# we will use enum class for creating enumerations


class Days(enum.Enum):
    Sunday = 1
    Monday = 2
    Tuesday = 1
    Wednesday = 4
    Thursday = 5
    Friday = 4
    Saturday = 7


# 1==1
if Days.Sunday == Days.Tuesday:
    print('Match')  # Match
else:
    print('Do not Match')

# 2!=1
if Days.Monday != Days.Tuesday:
    print('Do not Match')  # Do not Match
else:
    print('Match')

# 4==4
if Days.Wednesday == Days.Friday:
    print('Match')  # Match
else:
    print('Do not Match')

# 5!=4
if Days.Thursday != Days.Friday:
    print('Do not Match')  # Do not Match
else:
    print('Match')

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