subclassing | 易学教程

What to consider before subclassing list?

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I was recently going over a coding problem I was having and someone looking at the code said that subclassing list was bad (my problem was unrelated to that class). He said that you shouldn't do it and that it came with a bunch of bad side effects. Is this true? I'm asking if list is generally bad to subclass and if so, what are the reasons. Alternately, what should I consider before subclassing list in Python? There are no benefits to subclassing list . None of the methods will use any methods you override, so you can have unexpected bugs. Further, it's very often confusing doing things like

How do I include subclasses in Swagger API documentation/ OpenAPI specification using Swashbuckle?

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I have an Asp.Net web API 5.2 project in c# and generating documentation with Swashbuckle. I have model that contain inheritance something like having an Animal property from an Animal abstract class and Dog and Cat classes that derive from it. Swashbuckle only shows the schema for the Animal class so I tried to play with ISchemaFilter (that what they suggest too) but I couldn't make it work and also I cannot find a proper example. Anybody can help? Paolo Vigori It seems Swashbuckle doesn't implement polymorphism correctly and I understand the point of view of the author about subclasses as

Why do all backgrounds disappear on UITableViewCell select?

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My current project's UITableViewCell behavior is baffling me. I have a fairly straightforward subclass of UITableViewCell. It adds a few extra elements to the base view (via [self.contentView addSubview:...] and sets background colors on the elements to have them look like black and grey rectangular boxes. Because the background of the entire table has this concrete-like texture image, each cell's background needs to be transparent, even when selected, but in that case it should darken a bit. I've set a custom semi-transparent selected background to achieve this effect: UIView *background = [[

UIView subclass with its own XIB [duplicate]

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This question already has an answer here: UIView and initWithFrame and a NIB file. How can i get the NIB file loaded? 5 answers I created a custom UIView subclass, and would prefer to not layout the UI in code in the UIView subclass. I'd like to use a xib for that. So what I did is the following. I created a class "ShareView" which subclasses UIView. I created a XIB file with its file's owner set to "ShareView". Then I link some outlets I declared in my "ShareView.h". Next I have a ViewController, MainViewController, which adds the ShareView as a subview. whith this code: NSArray *arr = [

How to subclass pandas DataFrame?

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Subclassing pandas classes seems a common need but I could not find references on the subject. (It seems that pandas developers are still working on it: https://github.com/pydata/pandas/issues/60 ). There are some SO threads on the subject, but I am hoping that someone here can provide a more systematic account on currently the best way to subclass pandas.DataFrame that satisfies two, I think, general requirements: import numpy as np import pandas as pd class MyDF(pd.DataFrame): # how to subclass pandas DataFrame? pass mydf = MyDF(np.random.randn(3,4), columns=['A','B','C','D']) print type

Extending Generic Classes

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问题 public class MyGeneric<T, E> {} public class Extend1<T, E> extends MyGeneric<T, E> {} public class Extend2 extends MyGeneric<String, Object> {} As far as I am aware, both of the subclasses in the above example are valid. I was wondering how Java knows when the types given in the superclass are going to be defined when the subclass is instantiated, and when they are actual class names (i.e. How does it know T, E are not class names)? A side note, is it permissible (even if uncommon) to use

creating a defaultlist in python

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问题 I'm trying to create a list equivalent for the very useful collections.defaultdict. The following design works nicely: class defaultlist(list): def __init__(self, fx): self._fx = fx def __setitem__(self, index, value): while len(self) <= index: self.append(self._fx()) list.__setitem__(self, index, value) Here's how you use it: >>> dl = defaultlist(lambda:'A') >>> dl[2]='B' >>> dl[4]='C' >>> dl ['A', 'A', 'B', 'A', 'C'] What should I add to the defaultlist so as to support the following

Why can't you reduce the visibility of a method in a Java subclass?

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Why does the compiler give an error message when you reduce the visibility of a method while overriding it in the subclass? Joachim Sauer Because every instance of the subclass still needs to be a valid instance of the base class (see Liskov substitution principle ). If the subclass suddenly has lost one property of the base class (namely a public method for example) then it would no longer be a valid substitute for the base class. Because if this was allowed, the following situation would be possible: Class Sub inherits from class Parent. Parent has a public method foo , Sub makes that method

How do I include subclasses in Swagger API documentation/ OpenAPI specification using Swashbuckle?

阅读更多关于 How do I include subclasses in Swagger API documentation/ OpenAPI specification using Swashbuckle?

问题 I have an Asp.Net web API 5.2 project in c# and generating documentation with Swashbuckle. I have model that contain inheritance something like having an Animal property from an Animal abstract class and Dog and Cat classes that derive from it. Swashbuckle only shows the schema for the Animal class so I tried to play with ISchemaFilter (that what they suggest too) but I couldn't make it work and also I cannot find a proper example. Anybody can help? 回答1: It seems Swashbuckle doesn't implement

UIView subclass with its own XIB [duplicate]

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问题 This question already has answers here : UIView and initWithFrame and a NIB file. How can i get the NIB file loaded? (5 answers) Closed 4 years ago . I created a custom UIView subclass, and would prefer to not layout the UI in code in the UIView subclass. I'd like to use a xib for that. So what I did is the following. I created a class "ShareView" which subclasses UIView. I created a XIB file with its file's owner set to "ShareView". Then I link some outlets I declared in my "ShareView.h".