Pythonで変数が定義されているかどうかを判定する

global_var1 = 1000

def print_variable():
    local_var1 = 0

    print(globals())
    print(locals())
#;

if __name__ == "__main__":
    main_var1 = 10
    print_variable()

{ ..., 'global_var1': 1000, ..., 'main_var1': 10 }
{ 'local_var1': 0 }

def check_variable():
    local_var1 = 0

    if 'local_var1' in globals():
        print('local_var1 in globals')
    if 'local_var2' in globals():
        print('local_var2 in globals')
    if 'local_var1' in locals():
        print('local_var1 in locals')
    if 'local_var2' in locals():
        print('local_var2 in locals')

    if 'global_var1' in globals():
        print('global_var1 in globals')
    if 'main_var1' in globals():
        print('main_var1 in globals')
    if 'global_var1' in locals():
        print('global_var1 in locals')
    if 'main_var1' in locals():
        print('main_var1 in locals')
#;

global_var1 = 1000

if __name__ == "__main__":
    main_var1 = 10
    check_variable()

    if 'main_var1' in globals():
        print('[__main__] main_var1 in globals')
    if 'main_var1' in locals():
        print('[__main__] main_var1 in locals')

    if 'global_var1' in globals():
        print('[__main__] global_var1 in globals')
    if 'global_var1' in locals():
        print('[__main__] global_var1 in locals')

    if 'local_var1' in globals():
        print('[__main__] local_var1 in globals')
    if 'local_var1' in locals():
        print('[__main__] local_var1 in locals')
#;

local_var1 in locals
global_var1 in globals
main_var1 in globals
[__main__] main_var1 in globals
[__main__] main_var1 in locals
[__main__] global_var1 in globals
[__main__] global_var1 in locals