design-patterns

问题 Both Two-way Adapter and Pluggable Adapter can access both the classes and also change the behavior of the method which is required to be changed. The following is my code: Two-Way Adapter public interface IAircraft { bool Airborne { get; } void TakeOff(); int Height { get; } } // Target public sealed class Aircraft : IAircraft { int height; bool airborne; public Aircraft() { height = 0; airborne = false; } public void TakeOff() { Console.WriteLine("Aircraft engine takeoff"); airborne = true;

问题 I need to select files which start with "M" and end with " .csv". I can easily select files which start with "M" : list.files(pattern="^M"), or files which end with "csv": list.files(pattern = " .csv"). But how to select files which satisfy both conditions at the same time? 回答1: You could try glob2rx lf <- list.files("path_to_directory/", pattern=glob2rx("M*.csv")) which translates to: glob2rx("M*.csv") [1] "^M.*\\.csv$" 回答2: The pattern argument takes a regular expression: list.files(pattern

问题 I need to select files which start with "M" and end with " .csv". I can easily select files which start with "M" : list.files(pattern="^M"), or files which end with "csv": list.files(pattern = " .csv"). But how to select files which satisfy both conditions at the same time? 回答1: You could try glob2rx lf <- list.files("path_to_directory/", pattern=glob2rx("M*.csv")) which translates to: glob2rx("M*.csv") [1] "^M.*\\.csv$" 回答2: The pattern argument takes a regular expression: list.files(pattern

问题 I am always struggling with decoration + interfaces. Say I have the following 'behavior' interfaces : interface IFlyable { void Fly();} interface ISwimmable { void Swim();} A main interface interface IMainComponent { void DoSomethingA(); void DoSomethingB();} A decorator on the main interace public class Decorator : IMainComponent { private readonly IMainComponent decorated; [..] public virtual void DoSomethingA() { decorated.DoSomethingA(); } public virtual void DoSomethingB() { decorated

问题 I have to do a design of a DownloadManager , but my main question is related to the notifications that a Download can send to the DownloadManager like onUpdate() to update a progress bar, onError() , onFinish() , etc. Somehow the DownloadManager has to receive this notifications from its Download s. I've thought 2 possible ways: Observer pattern Callbacks Observer pattern Basically there are 1 Observable and N Observers. In my case the DownloadManager has te be an Observer and the Downloads

问题 I have to do a design of a DownloadManager , but my main question is related to the notifications that a Download can send to the DownloadManager like onUpdate() to update a progress bar, onError() , onFinish() , etc. Somehow the DownloadManager has to receive this notifications from its Download s. I've thought 2 possible ways: Observer pattern Callbacks Observer pattern Basically there are 1 Observable and N Observers. In my case the DownloadManager has te be an Observer and the Downloads

问题 I am designing a GUI that has the following basic idea (similarly modeled after Visual Studio's basic look-and-feel): File navigation Control selector (for selecting what to display in the Editor component) Editor Logger (errors, warnings, confirmation, etc.) For now, I will be using a TreeView for file navigation, a ListView for selecting controls to be displayed in the Editor and a RichTextBox for the Logger. The Editor will have 2 types of editing modes depending on what is selected in the

问题 I'm making Java REST application. I wonder how should I implement my services - should I use static service variables for whole application or make services as singletons like it was made in Spring MVC. Is there any difference between singleton object and initializing object only once during application? 回答1: should I use static service variables for whole application or make services as singletons It depends. You have to ask yourself two questions to come up with an answer: Where is that

问题 We have a set of about two dozen classes that inherit from a base class which has an abstract Validate method. Of course each class has different validation needs but the rules are needed in different combinations between all of them so, as you can imagine, this resulted in a lot of code duplication, as an example: Class A needs rules 1, 3, 6, and 9 Class B needs rules 3, 4, and 8 Class C needs rules 1, 8, and 9 .... you get the picture. So I was thinking of doing a simple refactoring and

问题 The template method pattern provides that the abstract base class has a not overridable method: this method implements the common algorithm and should not overridden in the subclasses. In Java the template method is declared final within the abstract base class, in C# the sealed keyword has a similar meaning, but a not overridden method can not be declared sealed . public abstract class Base { protected abstract AlgorithmStep1(); protected abstract AlgorithmStep2(); public sealed void