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defined?の罠

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たった一行のプログラムにはまったのでメモ

# variable_flagは未定義とする
variable_flag = defined?(variable_flag) ? true : false
puts variable_flag # true
# variable_flagは未定義とする
_variable_flag = defined?(variable_flag) ? true : false
puts _variable_flag # false

defined?で調べる変数の結果の代入先をその変数と同じにすると定義済み(true)結果が返る

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