Why is it best practice to initialize the instance variable within the constructor? Clarity. Because it makes it easy to see at a glance all of the attributes of the class. If you initialize the variables in multiple methods, it becomes difficult to understand the complete data structure without reading every line of code. Initializing … Read more
The issue has nothing to do with thread safety, really. There’s a simple, straightforward answer to why instance variables can always be captured: this is always effectively final. That is, there is always one known fixed object at the time of the creation of a lambda accessing an instance variable. Remember that an instance variable … Read more
Class attributes are accessible through the class: YourClass.clsattribute or through the instance (if the instance has not overwritten the class attribute): instance.clsattribute Methods, as stated by ecatmur in his answer, are descriptors and are set as class attributes. If you access a method through the instance, then the instance is passed as the self parameter … Read more
this answer doesn’t pollutes the class space, example.. if i do mine.my_number 4 then the other instances of Mine will not get the my_4 method.. this happens because we use the singleton class of the object instead of the class. class Mine def my_number num singleton_class.class_eval { attr_accessor “my_#{num}” } send(“my_#{num}=”, num) end end a … Read more
I would recommend using the first version, where you assign types to your __init__ method’s parameters, for most circumstances. That particular method has the least amount of redundancy while still allowing type checkers to verify that you’re calling that __init__ method correctly elsewhere in your code. I would recommend using either the second or third … Read more
I think you should avoid both solutions. Simply because you should avoid to create uninitialized or partially initialized objects, except in one case I will outline later. Look at two slightly modified version of your class, with a setter and a getter: class MyClass1: def __init__(self, df): self.df = df self.results = None def set_results(self, … Read more
Returning a value is preferable as it allows you to keep all the attribute modifying in one place (__init__). Also, this makes it easier to extend the code later; suppose you want to override _build_query in a subclass, then the overriding method can just return a value, without needing to know which attribute to set. … Read more
var should definitely not be shared as long as you access it by instance.var or self.var. With the list however, what your statement does is when the class gets evaluated, one list instance is created and bound to the class dict, hence all instances will have the same list. Whenever you set instance.list = somethingelse … Read more
a couple of ways I have done this in the past put the data in hidden fields, access the data in js/coffee # single value <%= hidden_field_tag “foo_name”, @foo.name, { :id => “foo-name” } %> $(‘#foo-name’).val(); # when the ‘value’ has multiple attributes <%= hidden_field_tag “foo”, @foo.id, { :id => “foo”, “data-first-name” => @foo.first_name, “data-last-name” … Read more