英文:
child class with extra arguments python class inheritance
问题
我编写了一个父类：```pythonclass Parent():def __init__(self, spark_session=None):try:# 实例化 Spark 会话self.spark = spark_sessionif not self.spark:self.spark = SparkSession.builder.config("spark.sql.debug.maxToStringFields", 1000).appName("SparkTest") \.getOrCreate()except Exception as e:print("初始化 Spark 和日志记录失败: {}".format(e))
然后子类在其构造函数中有一个额外的参数，即路径：
class Child(Parent):def __init__(self, path, spark=None):self.spark = super().__init__(spark)self.path = path
然后当我写下这段代码：
a = Child("path", None)print(a.spark)
对于：
self.spark = spark_session
我得到了：
AttributeError: 'NoneType' object has no attribute 'spark' None
有任何想要修复这个问题并使 Spark 对象按预期实例化的想法吗？
谢谢。
<details><summary>英文:</summary>I wrote a parent class:```pythonclass Parent():def __init__(self, spark_session=None):try:# Instantiate Spark Sessionself.spark = spark_sessionif not self.spark:self.spark = SparkSession.builder.config("spark.sql.debug.maxToStringFields", 1000).appName("SparkTest") \.getOrCreate()except Exception as e:print("Initialization of spark & logging couldn't be performed: {}".format(e))
Then the child class has an extra argument in its constructor which is path:
class Child(Parent):def __init__(self, path, spark=None):self.spark = super().__init__(spark)self.path = path
Then when I write this:
a = Child("path", None)print(a.spak)
For:
self.spark = spark_session
I get:
AttributeError: 'NoneType' object has no attribute 'spark' None
Any idea how to fix this and make spark object instantiate as expected.
Regards
答案1
得分: 1
self.spark = super().__init__(spark):
self.spark = super().__init__(spark):
self.spark = super().__init__(spark):
__init__ 不是构造函数。它初始化对象的属性并返回 None，而不是对象本身。
一旦调用 super().__init__，self.spark 将自动初始化。
请注意，我还稍微更改了 Parent.__init__。在您的代码中，如果引发异常，self.spark 没有定义，这将导致后续出现其他错误。
class Parent:def __init__(self, spark_session=None):self.spark = spark_sessiontry:if not self.spark:self.spark = SparkSession.builder.config("spark.sql.debug.maxToStringFields", 1000).appName("SparkTest") \.getOrCreate()except Exception as e:print("初始化 Spark 和记录无法执行: {}".format(e))class Child(Parent):def __init__(self, path, spark=None):super().__init__(spark)self.path = path
英文:
self.spark = super().__init__(spark)
__init__ is not a constructor. It initializes the object's attributes and returns None, not the object.
self.spark will be automatically initialized once you call super().__init__.
Note I also changed Parent.__init__ a bit. In your code self.spark is not defined in case an exception is raised which will lead to other errors down the road.
class Parent:def __init__(self, spark_session=None):self.spark = spark_sessiontry:if not self.spark:self.spark = SparkSession.builder .config("spark.sql.debug.maxToStringFields", 1000).appName("SparkTest") \.getOrCreate()except Exception as e:print("Initialization of spark & logging couldn't be performed: {}".format(e))class Child(Parent):def __init__(self, path, spark=None):super().__init__(spark)self.path = path
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