Pythonのグローバル変数について

Start Python Club #64 LT

Transcript

1. ̕,JPUP)JSBIBSB
   1ZUIPOͷ
   άϩʔόϧม਺ʹ͍ͭͯ
   4UBSU1ZUIPO$MVC-5
   

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2. ͓લɺ୭Α
   w ฏݪوԻʢͻΒ͸Β͖͓ͱʣ
   w ࡾӜ൒ౡͰϑϦʔϥϯεͷϓϩάϥϚͯ͠·͢
   w 4UBSU1ZUIPO$MVC໊ݹ԰ࢧ෦ελοϑ
   w 1ZUIPO#PPU$BNQJOח૔ͷݱ஍ελοϑʢ։࠵༧ఆʣ
   

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3. 1ZUIPO#PPU$BNQJOח૔ɹ։࠵͠·͢
   IUUQTQZDPOKQDPOOQBTTDPNFWFOU
   ೥݄೔ʢ౔ʣʙ
   )"546ח૔ʹͯ։࠵
   

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4. w ϞδϡʔϧείʔϓͰ୅ೖ͞Εͨม਺
   w ؔ਺಺ͰࢀরՄೳ
   άϩʔόϧม਺ͱ͸Կ͔
   # -*- coding:utf-8 -*-
   x = 0 # άϩʔόϧม਺
   def foo():
   print(x)
   foo()
   ˞1ZUIPO+BQBOθϩ͔Βͷ1ZUIPOೖ໳ߨ࠲
   ʮϩʔΧϧม਺ͱάϩʔόϧม਺ʯΑΓ
   IUUQTXXXQZUIPOKQUSBJOGVODUJPOMPDBM@WBSIUNM
   

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5. w ؔ਺಺Ͱ୅ೖͰ͖ͳ͍
   w ͦͷ··ͩͱϩʔΧϧม਺ʹͳΔ
   άϩʔόϧม਺ͱ͸Կ͔
   # -*- coding:utf-8 -*-
   x = 0 # άϩʔόϧม਺
   def bar():
   x = 999
   print(x)
   def foo():
   print(x)
   bar() # => 999
   foo() # => 0
   

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6. ؔ਺಺Ͱάϩʔόϧม਺Λ୅ೖ
   w HMPCBMจΛ࢖͏
   # -*- coding:utf-8 -*-
   x = 0
   def bar():
   global x
   x = 10
   def foo():
   print(x)
   bar()
   foo() # => 10
   

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7. HMPCBMจͷఆٛ
   w ެࣜυΩϡϝϯτΑΓ
   w
   HMPCBMจ͸ɺݱࡏͷίʔυϒϩοΫશମͰҡ࣋͞ΕΔએݴจͰ͢ɻ
   w
   HMPCBMจ͸ɺྻڍͨࣝ͠ผࢠΛάϩʔόϧม਺ͱͯ͠ղऍ͢ΔΑ͏ࢦ
   ఆ͢Δ͜ͱΛҙຯ͠·͢ɻ
   IUUQTEPDTQZUIPOPSHKBSFGFSFODFTJNQMF@TUNUTIUNM IJHIMJHIUHMPCBMUIFHMPCBMTUBUFNFOU
   

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8. HMPCBMจͷఆٛ
   # -*- coding:utf-8 -*-
   x = 0
   def bar():
   global x
   x = 10
   def foo():
   print(x)
   bar()
   foo() # => 10
   
   HMPCBMจ͸ɺݱࡏͷίʔυϒϩο
   ΫશମͰҡ࣋͞ΕΔએݴจͰ͢ɻ
   
   ݱࡏͷίʔυϒϩοΫ
   w
   HMPCBMจ͸ɺྻڍͨࣝ͠ผࢠΛ
   άϩʔόϧม਺ͱͯ͠ղऍ͢ΔΑ͏ࢦ
   ఆ͢Δ͜ͱΛҙຯ͠·͢ɻ
   
   ྻڍͨࣝ͠ผࢠ
   

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9. ʢඇਪ঑ʣϞδϡʔϧείʔϓͰະఆٛ
   w ϞδϡʔϧείʔϓͰະఆٛͰ΋ಈ͘
   w Մಡੑ͕ѱ͍
   ˠάϩʔόϧม਺Yͷॳظ஋͸ʁ
   ɹؔ਺ͷ࣮ߦॱংͷ֬ೝ͕ඞཁʹͳΔ
   # -*- coding:utf-8 -*-
   # x = 0
   def bar():
   global x
   x = 10
   def foo():
   print(x)
   bar()
   foo() # => 10
   

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10. ʢඇਪ঑ʣϞδϡʔϧείʔϓͰະఆٛ
    w ౰વɺઌʹࢀর͢ΔͱΤϥʔ
    # -*- coding:utf-8 -*-
    # x = 0
    def bar():
    global x
    x = 10
    def foo():
    print(x)
    foo() # ERROR!
    bar()
    

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11. ʢඇਪ঑ʣࢀর͚ͩͳͷʹHMPCBMจ
    w Մಡੑ͕ѱ͘ͳΔ
    w ୅ೖ͢Δͭ΋Γͩͬͨʁόάʁ
    # -*- coding:utf-8 -*-
    x = 0
    def bar():
    global x
    x = 10 # xʹ୅ೖ͍ͯ͠Δ
    def foo():
    global x
    print(x) # x͸୅ೖ͠ͳ͍ͷʁ
    bar()
    foo() # => 10
    

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12. ϩʔΧϧม਺ͷ༏ઌ
    w άϩʔόϧม਺ͱಉ໊ͷϩʔΧϧม਺͸ɺ
    ϩʔΧϧม਺͕༏ઌ
    w ʢͦ΋ͦ΋άϩʔόϧม਺YͬͯϩʔΧϧ
    ม਺ͱݟ෼͚͕͖ͭʹ͍͘ʂʣ
    # -*- coding:utf-8 -*-
    x = 0
    def foo():
    x = 10 # x͸ϩʔΧϧม਺
    print(x)
    foo() # => 10
    

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13. 1&1ͷάϩʔόϧม਺ͷ໋໊ϧʔϧ
    w ϞδϡʔϧείʔϓͰඇެ։ͳΒ͹ɺઌ಄
    ʹΞϯμʔείΞΛೖΕΔ
    w ࢀরൣғ͕޿͍ม਺͸ɺԿͷ஋͔෼͔Δ
    Α͏ʹɺͪΌΜͱҙຯͷ͋Δ໊લʹ͢Δ
    ͜ͱ
    # -*- coding:utf-8 -*-
    _value = 0
    def foo():
    global _value
    _value = 10
    y = 20
    print(_value, y)
    foo() # => 10, 20
    

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14. HMPCBMจͷҐஔ
    w HMPCBMจ͸ؔ਺ͷઌ಄Ͱͳͯ͘΋ಈ͘
    w ͨͩ͠ɺಡΈʹ͍͘ͷͰHMPCBMจ͸ؔ਺
    ͷઌ಄͕͍͍ʢݸਓͷײ૝ʣ
    # -*- coding:utf-8 -*-
    _value = 0
    def foo():
    y = 20
    global _value # OK
    _value = 10
    print(_value, y)
    foo() # => 10,20
    

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15. ༨ஊ
    w ʮάϩʔόϧʯ࣮ͬͯ͸ਖ਼֬Ͱ͸ͳ͍
    w ຊདྷɺͦͷ··Ͱ͸Ϟδϡʔϧείʔϓ֎͔ΒಁաͰͳ͍͔Β
    w ศ্ٓɺʮϞδϡʔϧείʔϓʯͷ͜ͱΛʮάϩʔόϧʯͱݺΜͰ͍Δ
    w 1ZUIPOͷެࣜจॻͰ΋ʮάϩʔόϧม਺ʯ͸࢖ΘΕ͍ͯΔ
    

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16. ଞͷϞδϡʔϧείʔϓͷม਺ࢀর
    w Α༷ͦͷάϩʔόϧม਺Λ࢖͏
    # -*- coding:utf-8 -*-
    import mymod
    def print_val():
    print(mymod.val)
    def set_val(num):
    mymod.val = num
    print_val() # => 0
    set_val(456)
    print_val() # => 456
    SVOQZ
    # -*- coding:utf-8 -*-
    val = 0
    NZNPEQZ
    

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17. ଞͷϞδϡʔϧείʔϓͷม਺ࢀর
    w Α༷ͦͷάϩʔόϧม਺Λɺࣗ෼ͷͱ͜Ζ
    ͷάϩʔόϧม਺ͱͯ͠࢖͏
    # -*- coding:utf-8 -*-
    from mymod import *
    def print_val():
    print(val)
    def set_val(num):
    global val
    val = num
    print_val() # => 0
    set_val(456)
    print_val() # => 456
    SVOQZ
    # -*- coding:utf-8 -*-
    val = 0
    NZNPEQZ
    

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18. ଞͷϞδϡʔϧείʔϓͷม਺ࢀর
    w ͞Βʹࣗ෼ͷͱ͜ΖͰάϩʔόϧม਺Λ࡞
    ΔͱɺNZNPEWBM͕ݟ͑ͳ͘ͳΔ
    w ͭ·Γ͜͏͍͏ॻ͖ํΛ͢΂͖Ͱͳ͍
    # -*- coding:utf-8 -*-
    from mymod import *
    val = 999
    def print_val():
    print(val)
    def set_val(num):
    global val
    val = num
    print_val() # => 999
    set_val(456)
    print_val() # => 456
    SVOQZ
    # -*- coding:utf-8 -*-
    val = 0
    NZNPEQZ
    

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19. ༨ஊ̎
    w ̎֊૚Ҏ্ͷ֊૚ͰɺHMPCBMจ͸ࢀরʹ΋࢖͑Δ
    w ͦ΋ͦ΋ϩʔΧϧม਺ͱಉ໊͡લͷάϩʔόϧม਺໊͸ɺͲ͏͔ͱࢥ͏
    Αɺͱ͍͏͜ͱͰඇਪ঑Ͱ͢
    w ໘౗ͳͷͰɺOPOMPDBMจͷ࿩͸͠·ͤΜ
    

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20. άϩʔόϧม਺ͷࢀর
    w ̎֊૚ͷؔ਺ఆٛͷྫ
    # -*- coding:utf-8 -*-
    x = 0
    def func01():
    x = 99
    def func02():
    # global x
    print('func02', x)
    func02()
    print('func01', x)
    func01()
    => func02 99
    => func01 99
    SFTVMU
    
    

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21. άϩʔόϧม਺ͷࢀর
    w ̎֊૚ͷؔ਺ఆٛͷྫ
    ʢHMPCBMจ௥Ճʣ
    # -*- coding:utf-8 -*-
    x = 0
    def func01():
    x = 99
    def func02():
    global x
    print('func02', x)
    func02()
    print('func01', x)
    func01()
    => func02 0
    => func01 99
    SFTVMU
    
    

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22. ༨ஊ
    w ಉ໊ͷϩʔΧϧม਺ͱάϩʔόϧม਺͸ɺಉ͡είʔϓͰ࢖͑ͳ͍
    $ python3 sample.py
    File "sample.py", line 8
    global x
    ^
    SyntaxError: name 'x' is used
    prior to global declaration
    # -*- coding:utf-8 -*-
    x = 0
    def foo():
    x = 10
    print(x)
    global x
    x = 20
    print(x)
    foo()
    SFTVMU
    
    

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