Pythonのグローバル変数について

Start Python Club #64 LT

Transcript

1. ̕
   
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2. ͓લɺ୭Α w ฏݪ
   وԻʢͻΒ͸Β
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   w ࡾӜ൒ౡͰϑϦʔϥϯεͷϓϩάϥϚͯ͠·͢
   w 4UBSU
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   w 1ZUIPO
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   JO
   ח૔ͷݱ஍ελοϑʢ
   ։࠵༧ఆʣ
3. 1ZUIPO
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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
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   θϩ͔Βͷ1ZUIPOೖ໳ߨ࠲
   
   ʮϩʔΧϧม਺ͱάϩʔόϧม਺ʯΑΓ
   IUUQTXXXQZUIPOKQUSBJOGVODUJPOMPDBM@WBSIUNM
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
6. ؔ਺಺Ͱάϩʔόϧม਺Λ୅ೖ w HMPCBMจΛ࢖͏ # -*- coding:utf-8 -*- x = 0 def bar(): global x x = 10 def foo(): print(x) bar() foo() # => 10
7. HMPCBMจͷఆٛ w ެࣜυΩϡϝϯτΑΓ
   w 
   HMPCBM
   จ͸ɺݱࡏͷίʔυϒϩοΫશମͰҡ࣋͞ΕΔએݴจͰ͢ɻ
   w 
   HMPCBM
   จ͸ɺྻڍͨࣝ͠ผࢠΛάϩʔόϧม਺ͱͯ͠ղऍ͢ΔΑ͏ࢦ ఆ͢Δ͜ͱΛҙຯ͠·͢ɻ IUUQTEPDTQZUIPOPSHKBSFGFSFODFTJNQMF@TUNUTIUNM IJHIMJHIUHMPCBMUIFHMPCBMTUBUFNFOU
8. HMPCBMจͷఆٛ # -*- coding:utf-8 -*- x = 0 def bar(): global x x = 10 def foo(): print(x) bar() foo() # => 10 
   HMPCBM
   จ͸ɺݱࡏͷίʔυϒϩο ΫશମͰҡ࣋͞ΕΔએݴจͰ͢ɻ 
   ݱࡏͷίʔυϒϩοΫ w 
   HMPCBM
   จ͸ɺྻڍͨࣝ͠ผࢠΛ άϩʔόϧม਺ͱͯ͠ղऍ͢ΔΑ͏ࢦ ఆ͢Δ͜ͱΛҙຯ͠·͢ɻ 
   ྻڍͨࣝ͠ผࢠ
9. ʢඇਪ঑ʣϞδϡʔϧείʔϓͰະఆٛ w ϞδϡʔϧείʔϓͰະఆٛͰ΋ಈ͘
   w Մಡੑ͕ѱ͍
   ˠ
   άϩʔόϧม਺Yͷॳظ஋͸ʁ
   ɹ
   ؔ਺ͷ࣮ߦॱংͷ֬ೝ͕ඞཁʹͳΔ # -*- coding:utf-8 -*- # x = 0 def bar(): global x x = 10 def foo(): print(x) bar() foo() # => 10
10. ʢඇਪ঑ʣϞδϡʔϧείʔϓͰະఆٛ w ౰વɺઌʹࢀর͢ΔͱΤϥʔ # -*- coding:utf-8 -*- # x = 0 def bar(): global x x = 10 def foo(): print(x) foo() # ERROR! bar()
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
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
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
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
15. ༨ஊ w ʮάϩʔόϧʯ࣮ͬͯ͸ਖ਼֬Ͱ͸ͳ͍
    w ຊདྷɺͦͷ··Ͱ͸Ϟδϡʔϧείʔϓ֎͔ΒಁաͰͳ͍͔Β
    
    w ศ্ٓɺʮϞδϡʔϧείʔϓʯͷ͜ͱΛʮάϩʔόϧʯͱݺΜͰ͍Δ
    w 1ZUIPOͷެࣜจॻͰ΋ʮάϩʔόϧม਺ʯ͸࢖ΘΕ͍ͯΔ
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
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
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
19. ༨ஊ̎ w ̎֊૚Ҏ্ͷ֊૚ͰɺHMPCBMจ͸ࢀরʹ΋࢖͑Δ
    w ͦ΋ͦ΋ϩʔΧϧม਺ͱಉ໊͡લͷάϩʔόϧม਺໊͸ɺͲ͏͔ͱࢥ͏ Αɺͱ͍͏͜ͱͰඇਪ঑Ͱ͢
    w ໘౗ͳͷͰɺOPOMPDBMจͷ࿩͸͠·ͤΜ
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
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
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