How to work with read-only collections in C#

A selection represents a set of objects utilized for the storage and retrieval of facts. Collections help you to allocate memory dynamically to store aspects and then retrieve them using a crucial or index as required.

You can have common or generic collections. Whilst common collections really do not give style-security, generic collections are style-risk-free. The common collections are component of the System.Collections namespace, and the generic collections are component of the System.Collections.Generic namespace.

An immutable object is defined as an object that can not be altered after it has been established. Not all collections are immutable, but you can use the browse-only selection styles in .Internet Main these kinds of as IReadOnlyList, IReadOnlyDictionary, and IReadOnlyCollection to implement immutable styles. These all are component of the System.Collections.Generic namespace.

How to avoid GC pressure in C# and .NET

This write-up discusses these browse-only immutable selection styles in .Internet Main and how you can work with them in C#. To work with the code illustrations supplied in this write-up, you should have Visual Studio 2019 mounted in your program. If you really do not previously have a copy, you can obtain Visual Studio 2019 below.

Create a console application challenge in Visual Studio

1st off, let us develop a .Internet Main console application challenge in Visual Studio. Assuming Visual Studio 2019 is mounted in your program, follow the measures outlined below to develop a new .Internet Main console application challenge in Visual Studio.

Start the Visual Studio IDE.
Simply click on “Create new challenge.”
In the “Create new project” window, pick “Console Application (.Internet Main)” from the list of templates exhibited.
Simply click Next.
In the “Configure your new project” window revealed subsequent, specify the title and area for the new challenge.
Simply click Create.

This will develop a new .Internet Main console application challenge in Visual Studio 2019. We’ll use this challenge in the subsequent sections of this write-up.

Examine-only collections, dictionaries, and lists in .Internet Main

The IReadOnlyCollection interface extends the IEnumerable interface and represents a essential browse-only selection interface. It also features a Depend property apart from the IEnumerable users as revealed in the code snippet supplied below.

IReadOnlyCollection facts = products
int numOfRecords = facts.Depend

The IReadOnlyDictionary interface gives a browse-only view of a dictionary and represents a browse-only selection of crucial/worth pairs. The next code snippet illustrates how you can determine an IReadOnlyDictionary occasion.

community IReadOnlyDictionary Dictionary  get  = new Dictionary
        
             "1", "ABC" ,
             "two", "XYZ" ,
             "three", "PQR" ,

The IReadOnlyList interface pertaining to the System.Collections.Generic namespace represents a browse-only list, i.e., a browse-only selection of aspects that can be accessed by index.

Note that the IReadOnlyList interface functions likewise to Checklist and in simple fact can be utilized in spot of Checklist when you want the aspects of the list to be browse-only. We will illustrate this with an instance in the subsequent segment.

Use IReadOnlyList as a substitute of Checklist in C#

Let us discover an instance of using IReadOnlyList in spot of Checklist in purchase to make our list browse-only. Take into account the next course:

community course Author

   community int Id  get set 
   community string FirstName  get set 
   community string LastName  get set

Suppose you have to have to return a list of all authors from the database as revealed in the code snippet supplied below.

community static Checklist GetAuthors()

   return new Checklist
   
       new Author
       
           Id = 1,
           FirstName = "Joydip",
           LastName = "Kanjilal"
       ,
       new Author
       
           Id = two,
           FirstName = "Steve",
           LastName = "Smith"

For the sake of simplicity, we’re omitting the code important to retrieve facts (i.e., creator information) from the database. The next code snippet shows how you can contact the GetAuthors method from the Main method.

static void Main(string[] args)

    var authors = GetAuthors()
    Console.Examine()

If you acquire gain of IntelliSense in Visual Studio to see the users of the authors list object, you are going to see a list of techniques supported by Checklist. Figure 1 below shows the users of Checklist. Note that you have a method named Incorporate, so you can conveniently increase authors to the list of authors we’ve established in the previous code snippet.

IDG

Figure 1.

The selection utilized below is obviously mutable in nature. So how do you protect against this facts from getting altered?

Here’s where by you can acquire gain of IReadOnlyList to be certain that the returned facts can not be altered. By switching the return style of the GetAuthors method from Checklist to IReadOnlyList we can make our selection browse-only.

The next code snippet illustrates how IReadOnlyList can be utilized in spot of Checklist in the higher than method.

community static IReadOnlyList GetAuthors()

   return new Checklist
   
      new Author
      
          Id = 1,
          FirstName = "Joydip",
          LastName = "Kanjilal"
      ,
      new Author
      
          Id = two,
          FirstName = "Steve",
          LastName = "Smith"

Now when you use IntelliSense to examine IReadOnlyList, you are going to no lengthier see Incorporate among the the supported techniques. Figure two below shows the users of the IReadOnlyList occasion.

IDG

Figure two.

Use the IEnumberable interface in C#

The IEnumerable interface is however a different interface utilized normally to stand for browse-only collections of facts. If you only want to enumerate the aspects of a selection, you can use IEnumerable as revealed below.

community void MyMethod(IEnumerable authors)

  foreach (Author creator in authors)
  
      //Produce your code below

Nevertheless, if you want to access the aspects of the IEnumerable selection by index or you want to retrieve the variety of aspects in the selection, you should use IReadOnlyList as revealed below.

community void MyMethod(IReadOnlyList authors)

  int count = authors.Depend
  for(int index =  index < count index++)
  
      var creator = authors[index]
      //Produce your code below

IEnumerable has been utilized to stand for a browse-only selection of facts since the earliest versions of .Internet. The browse-only selection interfaces out there in .Internet Main and .Internet 5 help you to layout classes that protect against the collections from getting modified. Nevertheless, it should be famous that when these browse-only selection styles give a browse-only view of the facts, they are only wrappers. They do not give an immutable copy of the selection.

M	T	W	T	F	S	S
						1
2	3	4	5	6	7	8
9	10	11	12	13	14	15
16	17	18	19	20	21	22
23	24	25	26	27	28	29
30	31

25 Best Vegan Protein Powders in 2022

Estimate Traffic Stats By Channels & Date

Qlik unveils 2022 roadmap for its analytics platform

How to work with read-only collections in C#

Related Posts:

Create a console application challenge in Visual Studio

Examine-only collections, dictionaries, and lists in .Internet Main

25 Best Vegan Protein Powders in 2022

Estimate Traffic Stats By Channels & Date

Qlik unveils 2022 roadmap for its analytics platform

How to work with read-only collections in C#

Related Posts:

Create a console application challenge in Visual Studio

Examine-only collections, dictionaries, and lists in .Internet Main

‘Massive messaging storm’ takes out Telstra’s DNS infrastructure – Security – Telco/ISP

Air Quality is Worse in African American Neighborhoods. This Community is Fighting Pollution with Data

UK IT leaders show preference for cloud-first strategies