self

问题 I'm learning Python OOP and trying to convert a Java class to a Python class See page 15 in this PDF for Java code google doc link class QuickFindUF: """docstring for QuickFindUF""" def __init__(self, n): self.id = [] for e in range(n): self.id.append(e) def connected(self,p,q): return self.id[p]==self.id[q] def union(self,p,q): self.pid = self.id[p] self.qid = self.id[q] for i in range(len(self.id)): if(self.id[i]==self.pid): self.id[i]=self.qid quf = QuickFindUF(9) quf.union(3,4) print quf

问题 Some Scala APIs alias this to self , for example, trait Function1[-T1, +R] extends AnyRef { self => I know how this aliasing works in general, but don't see how traits such as Function1 benefit from it. Function1 does not use self anywhere in its definition except for the initial mention, so what is its purpose here? Variants of this question have been asked previously, but the answers are not directly applicable. Answers have discussed self types and inner classes, but I don't see how that

问题 Using ctypes to interface my python3 code with a C API. One of the C functions registers a callback function– i.e. it takes a function pointer to the callback and a void* userdata to be made available in that callback. // typedef and C function in myClibrary.so typedef void(__cdecl *callback_function_type)(void*); int RegCallback(callback_function_type callback_function, void* userbdata); I have successfully defined the required callback function type in python using CFUNCTYPE() , passed an

问题 Using ctypes to interface my python3 code with a C API. One of the C functions registers a callback function– i.e. it takes a function pointer to the callback and a void* userdata to be made available in that callback. // typedef and C function in myClibrary.so typedef void(__cdecl *callback_function_type)(void*); int RegCallback(callback_function_type callback_function, void* userbdata); I have successfully defined the required callback function type in python using CFUNCTYPE() , passed an

问题 I am python Begineer and i learned that first parameter inside the method should be contain some 'self' keyword but i found the following program runs without self keyword can you explain about this below is my code... class Student(object): def __init__(self,name,age): self.name = name self.age = age def get_biggest_number(*age): result=0 for item in age: if item > result: result= item return result Sam = Student("Sam",18) Peter = Student("Peter",20) Karen = Student("Karen",22) Mike =

问题 I have this kind of structure: class Foo: def __init__(self, val1): self.val1 = val1 def changeToGoo(self) HOW??? class Goo(Foo): def __init__(self, val1, val2): super(val1) self.val2 = val2 a = Foo(1) a.changeToGoo() 'a' is now an instance of Foo now i would like to change it to be an instance of Goo, by using the method "changeToGoo", and add the other value. How can this be done in Python? I have tried: self.__class__ = Goo but when I check: type(a) it's still Foo, and not Goo. 回答1: In

问题 class LinkedNode<T> { var value: T var next: Self? required init(_ value: T) { self.value = value } } class DoublyNode<T>: LinkedNode<T> { weak var previous: DoublyNode? override var next: Self? { didSet { next.previous = self } } } I wish it compiles like this. But it doesn't. Stored property cannot have covariant 'Self' type I have to rewrite the code to make it compile and work: class LinkedNode<T> { var value: T var next: LinkedNode? required init(_ value: T) { self.value = value } }

问题 class LinkedNode<T> { var value: T var next: Self? required init(_ value: T) { self.value = value } } class DoublyNode<T>: LinkedNode<T> { weak var previous: DoublyNode? override var next: Self? { didSet { next.previous = self } } } I wish it compiles like this. But it doesn't. Stored property cannot have covariant 'Self' type I have to rewrite the code to make it compile and work: class LinkedNode<T> { var value: T var next: LinkedNode? required init(_ value: T) { self.value = value } }

问题 class LinkedNode<T> { var value: T var next: Self? required init(_ value: T) { self.value = value } } class DoublyNode<T>: LinkedNode<T> { weak var previous: DoublyNode? override var next: Self? { didSet { next.previous = self } } } I wish it compiles like this. But it doesn't. Stored property cannot have covariant 'Self' type I have to rewrite the code to make it compile and work: class LinkedNode<T> { var value: T var next: LinkedNode? required init(_ value: T) { self.value = value } }

问题 class LinkedNode<T> { var value: T var next: Self? required init(_ value: T) { self.value = value } } class DoublyNode<T>: LinkedNode<T> { weak var previous: DoublyNode? override var next: Self? { didSet { next.previous = self } } } I wish it compiles like this. But it doesn't. Stored property cannot have covariant 'Self' type I have to rewrite the code to make it compile and work: class LinkedNode<T> { var value: T var next: LinkedNode? required init(_ value: T) { self.value = value } }