Questions tagged [delegates]
The delegates tag has no usage guidance.
48 questions
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3
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views
Are there any benefits to delegation over subclassing/inheritance in the case of a singleton?
Example:
The MacOS API known as Cocoa uses Delegation to specify various behaviors within the app. A Delegate is a separate object that implements a set of methods that are called by an original ...
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-2
votes
1
answer
152
views
Resorted to Unconventional( i.e., hacky) "circuitous" programming code techniques when using populating a list of C# Action Delegates via a for loop [closed]
AWS Amazon.S3.Model.PutObjectRequest is merely a 3rd-party AWS Data Transfer Object (DTO) / Plain Old C# Object (POCO) type that can be used to build a request that can be used to send requests to an ...
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2
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1
answer
174
views
Functions vs Classes for delegate pattern
Please consider the following sample
#include <cstdio>
#include <functional>
#include <memory>
#include <utility>
class PaintDelegate {
public:
virtual ~...
- 241
2
votes
1
answer
186
views
How to refactor same block of delegate code into a single private method?
I have these lines in multiple test methods. Now, trying to create a private method to clean up but not sure how to do it. Any suggestion or pointer would be really helpful. Thanks.
var ...
- 131
38
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10k
views
Why do heavily object-oriented languages avoid having functions as a primitive type?
As has been covered to the point of parody, heavily object-oriented languages, such as C# or Java, tend to lack the feature of having functions as a primitive type. You can argue about whether or not ...
- 1,037
0
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2
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586
views
Turn an asynchronous delegate pattern into a blocking method
I have to use a built-in API that works like this
class MyAPIWrapper {
func callAPI() {
apiObj.delegate = self
apiObj.doWork() // returns immediately, eventually calls self.delegate....
- 186
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2
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528
views
Design issue with delegation, inheritance and dependency injection
My question relates to usage of delegation together with inheritance and dependency injection.
I have a MailerService class that requires a delegate in order to do its job.
Furthermore, I have a ...
- 191
2
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2
answers
4k
views
Fundamental differences between a List<Action> vs Action
Is there any fundamental difference between to using an action and a list of actions? Seeing that action is a delegate and therefore is a list itself. For instance:
List<Action> ...
- 335
0
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1
answer
328
views
How to generalize which delegate is being used from an interface
I currently have the following set up where I have 2 or 3 classes implementing IZoneController and I have a set of conditions determining which function they need to execute when called. I first ...
-1
votes
3
answers
432
views
Refactoring - Resolve dependencies between legacy code used by third parties
I am developing two libraries in .Net
Firs one it's a library with core functionality (named it Library.Core.dll)
Let's focus in User class
public class User
{
//set of constructors and ...
- 622
4
votes
2
answers
1k
views
Is there an Ideal way of storing namespace-related elements?
In the title, with namespace-related elements, I refer to Enums, Delegates and other elements that do not belong to a single class, but to the whole namespace, or application.
I know that I can cram ...
- 181
19
votes
5
answers
7k
views
Using Func instead of interfaces for IoC
Context: I am using C#
I designed a class, and in order to isolate it, and make unit testing easier, I am passing in all its dependencies; it does no object instantiation internally. However, instead ...
- 5,291
4
votes
1
answer
5k
views
Is it possible to method-inject an object call?
Consider this example of method injection:
static void SaveEmail(Func<string> getEmailFunction)
{
dbcontext.SaveEmail(getEmailFunction());
}
static string GetEmail()
{
var frmUser = ...
- 26.9k
1
vote
2
answers
192
views
What is 'better' - An event that tells you that something happened or accepting a delegate to be called when the event triggers internally?
I am writing a collection that accepts a time parameter, the purpose is that after that specified amount of time have passed the element won't be present in the collection.
I want the user of this ...
- 567
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0
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67
views
If a delegate contains a tail call request, what happens?
Simply put, what happens when I have a delegate, that delegate contains a method with a tail call request, and then I call it from a non-tail position?
If I called the method directly, it would ...
- 110k
14
votes
3
answers
6k
views
Why aren't properties implicitly convertible to delegates
We all know that properties in C# get compiled to actual plain old methods. But unlike method(-group)s, they can't be given as arguments to other methods that expect a delegate like a Func<T> or ...
- 2,579
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1
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834
views
Is it a good practice to use a Service without Delegate?
I have a simple REST application with a single controller. The application needs to fetch data from a Database, convert it to JSON and return this to the caller.
I need to decide what layers I should ...
- 549
4
votes
1
answer
141
views
Using delegates as named lambdas
Suppose we have a domain in which we can generalise some operation by passing in a function, like the Select \ map functions. Now suppose that the function we pass in has some domain specific name, ...
- 6,036
6
votes
3
answers
5k
views
Differences between "first-class function" mechanisms
Some languages (Javascript, Python) have the notion that a function is an object:
//Javascript
var fn = console.log;
This means that functions can be treated like any other object (first-class ...
- 693
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votes
1
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2k
views
Strategy Pattern not sufficient for my problem?
Let me sketch the situation:
I have multiple users, with certain properties (2 enums)
For each user I need to fetch data, for some with some basic filtering, for some extended filtering (= basic ...
- 135
2
votes
1
answer
5k
views
What is the difference between Adapter and Delegation design pattern?
I am very confused about Adapter and Delegation design pattern. In Adapter pattern we bring an intermediate class to interact with another class. And in Delegation pattern we also bring an ...
- 315
2
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1
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184
views
how to split up a delegate class
I have a communication class that incapsulates all the apis of a remote application.
This class happens to be a delegate class because it is interchangeable with another one (the remote application ...
1
vote
3
answers
2k
views
Using delegates to avoid duplicate creation of resources
I'm writing a PCL that uses an HttpClient to go visit a few sites and extract data from them. My initial code looked like this:
public static class Download
{
public async static Task<byte[]&...
- 358
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3
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264
views
Many different classes that need similar functionality. Best approach?
I have many (at the moment around 30) different message classes in an application I am creating. Each of these messages need to be serialized and deserialized. However, the process of serializing and ...
- 91
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2
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418
views
Why aren't field-like events implemented as a list of delegates?
tl;dr: Why are field-like events implemented as a single delegate field? Wouldn't it be more straight-forward to use a list of delegates, thereby eliminating the null special case and avoiding all the ...
- 9,838
2
votes
1
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2k
views
Avoiding closures
I have a data structure in the form of a tree. Each node represents a cardboard box. The boxes can contain child boxes.
public class CardboardBox
{
public int Id {get; set;}
public int ...
- 123
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votes
1
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103
views
Is it ok for a for a View to dismiss itself?
Currently, I'm working on a project in which a view is dismissing itself.
While talking to another programmer on the team for this project, he said that it's fine (in that it behaves correctly), but ...
- 145
2
votes
1
answer
788
views
Generic delegates (C#) in Scala?
I wanted to know if there is an equivalent of the C# generic delegates in Scala.
The reference website is: http://msdn.microsoft.com/en-us/library/dd233060.aspx
I'm trying to make a complete ...
2
votes
2
answers
2k
views
Understanding C# Delegates Structure
I've been trying to understand C# delegates using Pro C# 5.
In short, the author describes the motivation for delegates as a structured way of dealing with function pointers and callbacks or two-way ...
- 552
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0
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59
views
Own Exception or Delegation design pattern to exit a program?
I am writing an application in Java which use MVC pattern design. I have 4 major classes: Main, Controller, Model, View. Main initialize the other three and run launchMenu() in a infinite loop, a ...
- 101
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412
views
Delegate method privately called from delegate itself?
One has established design patterns so ingrained in their brain, that when sometimes somebody does something unexpected, it is a revelation.
My colleague in an iOS project did call the delegate ...
- 628
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1
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79
views
Is it fine for a class that creates objects to delegate them?
I have a large list of intercommunicating components; so I decided to have one class create all of them and then subsequently delegate them to other classes to facilitate finer tweaking and wiring ...
- 945
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4
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3k
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C# Delegates are immutable - but why does that matter?
This is a followup question to this other question.
Background
Working from the MSDN Delegates Tutorial (C#), I see the following:
Note that once a delegate is created, the method it is ...
- 673
29
votes
7
answers
21k
views
Why would I ever use delegates if I'm not doing events? [duplicate]
I am trying to learn how to do events in C#, and according to the MSDN Events tutorial,
Events are declared using delegates. If you have not yet studied the Delegates Tutorial, you should do so ...
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votes
6
answers
3k
views
Do delegates defy OOP
I'm trying to understand OOP so I can write better OOP code and one thing which keeps coming up is this concept of a delegate (using .NET). I could have an object, which is totally self contained (...
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3k
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Why use protocol, not call the method directly?
I was asked this question in an interview. For eg: UITableviewDelegate protocol has CellForRowAtIndexpath. Why make it a delegate method in a protocol not a method in the UITableView class and call it ...
- 41
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votes
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22k
views
What is Delegation and why is it important in iOS programming?
At the moment I am teaching myself iOS programming, and one concept I find really hard to wrap my head around is delegation. What is it? Why and how is it used? What is the advantage? The technical ...
- 272
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votes
2
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1k
views
Template method within one class without subclasses or inheritance
I have an algorithm with mostly invariant parts that needs to be reused within one class so as to stay DRY.
Code duplication with repeating method structure
public void save(String key, int value) {...
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5
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27k
views
What are the advantages of the delegate pattern over the observer pattern?
In the delegate pattern, only one object can directly listen to another object's events. In the observer pattern, any number of objects can listen to a particular object's events. When designing a ...
- 1,495
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votes
2
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5k
views
MVC and delegation
I am a beginning iOS programmer and use the Model-View-Controller model as a design pattern: my model doesn't know anything about my view (in order to make it compatible with any view), my view doesn'...
- 173
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votes
2
answers
4k
views
Strategy vs Delegates
Can the Strategy design pattern entirely replace delegates?
In Java, for example, there are no delegates. Is it possible to gain all the features of delegates by using Strategy design pattern?
Edit:...
- 7,353
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votes
1
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2k
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Need to process 2 million 100k messages per second and route them to a particular event, delegate or multicast delegate
I need to process 2 million messages per second (perhaps in a scale out configuration) and route each message to a N delegates or multicast delegates.
Question
How should I structure my application in ...
- 6,060
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votes
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638
views
Delegates and events
What is the difference between
public delegate void SecondChangedHandler(Object clock, TimeInfoEventArgs ti);
public event SecondChangedHandler OnSecondChanged;
and
public event EventHandler<...
- 63
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votes
2
answers
2k
views
How do delegates fit into ASP.NET?
A developer told me they used delegates to bind most of their events in ASP.NET. Until then, I did not even know it was possible to use delegates in ASP.NET in a meaningful way.
My understanding ...
- 11.1k
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votes
4
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975
views
Can you overuse delegates and events
I've just started getting to grips with event driven programming and I'm finding delegates and events to be very useful. Since starting to see the potential I've began using them all the time to solve ...
- 403
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votes
5
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715
views
Delegate vs Method
Is there any advantige using delegates instead of methods? For example:
public void LoginAuthenticate(object sender, AuthenticateEventArgs e)
{
if (Membership.ValidateUser(lgUserLogin.UserName, ...
- 121
2
votes
2
answers
816
views
Delegate pattern for retrieving data v.s. using simple setters
I am considering using the Delegate Pattern to get some data necessary for an operation. There are a few different pieces of data that the algorithm needs to run, but they all have default values that ...
- 269
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10
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57k
views
Real world use of C# Delegates [closed]
I think that I conceptually understand C# delegates, however, I am struggling to find a real world example where they would be useful. Can you provide some answers detailing how C# delegates were ...
- 1,337