You cannot change it once initialized. Primarily I came up with this "very simple code": internal class Person { public string name; public int age; public string lname; public Person (string name, int age, string lname) { this. resharper_not_accessed_positional_property_local_highlighting. C# 6. When you add an element to the set, it will find the hash code using IEqualityComparer<T>. _pd. It calls Object. Reversed. It seems wanting to do something like the latter is fairly common; perhaps the best solution I've seen is to just define a struct outside the method. GetHashCode () ==> false. The method: ; calls the method System. This is probably to conform with the existing convention of readonly struct vs struct similarly with readonly record struct and record struct, which makes sense but is a bit contradictory to a normal reference type. Field: readonly T myField; Property: T myProp { get; } Since it would be very not feasible to detect if a class is immutable, we should probably eliminate that entirely aside from string perhaps. This simply restates the behaviour of readonly without explaining why it's bad to use readonly. I think you misunderstood. Suggestions came in this line of code: return this. In general, for mutable reference types, you should override GetHashCode only if:. GetHashCode End Function If you do decide to write your own hash code from scratch, you must ensure that it always returns the same hash code for a given set of values. the easiest way to calculate the GetHashCode is to simply xor (^) all the gethashcodes of the elements. A member of a type is either declared by the type or inherited from a base type, so the Type object returned by the DeclaringType property might not be the same as the Type object used to obtain the current MemberInfo object. Combines six values into a hash code. Dim display As New DisplayString () display. So: I don't think there's a good solution here, except perhaps to use a different property-grid implementation, or to add a dummy writable property - sorry!Remarks. Using readonly you can set the value of the field either in the declaration, or in the constructor of the object that the. return this. That way Dictionary and HashSet still works, but it will be the worst time complexity for key lookup, since all instances will "collide". Arrays in . This suggestion is invalid because no changes were made to the code. This applies both for get -only properties, and properties marked [ReadOnly(true)] . It seems to me that all most answers here were sidetracked into talking about immutability or hashcode guarantees, instead of answering the original question. So I find this advice by Microsoft on How to write safe and efficient C# code confusing:. C. internal class Person {. This leaves the list of applicable members for a GetHashCode () implementation to: Readonly fields And getter-only properties That are immutable structs And aren't static. You can also use a mapped type to make the type mutable, but it only works for public properties:Declare a new non-readonly property; Have static properties; Have dynamic properties. The identity of entities is based on an unique identifier scheme. I think it's better explain on example why you should override GetHashCode when you override equality members, and also why you should not use mutable. cs; SymbolInfo. With property WidgetName you can only change access to field _widgetName, not the value. To create a read-only property in TypeScript, you need to use the readonly keyword. A const field can only be initialized at the declaration of the field. Equals(Object). (co-author and co-editor). What you can't have is spans as fields, except on ref struct types. // Sample for the Environment. 7. GetHashCode () - you do not want to include the object. GetHashCode () and b. The property would act as a proxy to get the span from. Is it possible in MVC 3 to set a ReadOnly Attribute to true or false on Model depending of a property in the same class? maybe something like : ReadOnly ( (yyy)?false:true) public double? xxx { get; set; } I need to do it in the model or in the controller. position); } public readonly struct Location2 { // The order matters! // The default GetHashCode version will get a hashcode of the first field public int Position. In your case, with a property as a list you probably need a comparer, unless you made the list read only. Improve this answer. In an object destructuring pattern, shape: Shape means “grab the property shape and redefine it locally as a variable named Shape. The following example creates a collection that contains elements of the Box type and then searches it for a box matching another box by calling the FindFirst method, twice. Select one or more items in the Solution Explorer to make fields readonly in the files under these nodes and their child items. GetHashCode should use only readonly fields in order to return a consistent value. 2 introduces the third way of passing arguments: using in -modifier. The only thing I didn't like about this is the Default property violates the purity assumption of a property getter. IImmutableStack<T>. Property assignments should not be made for "readonly" fields not constrained to reference types BugFlags enumerations should explicitly initialize all their members Bug"GetHashCode" should not reference mutable fields BugResults of integer division should not be assigned to floating point variables BugI suspect it is because of the array method handler. If you let R# generate those equality members, it overrides the GetHashCode () function as well. 0 on the record. Exceptions. With all that said, if you want to be on the safe side make sure that your override of GetHashCode() returns the same value during the object's lifetime. Code Inspection: Nullable attribute usage with declaration having value or void type. The reflexive property: x. If you override the equals method to do a special comparison of two objects and the two objects are considered the same by the method, then the hash code of the two objects must also be the same. 同事轉來ReSharper的警告：Non-readonly fields referenced in GetHashCode()，GetHashCode的計算來源必須保證不會變動，而使用readonly欄位是最直接有效的做法。而我這才注意，MSDNTwoDPoint範例，其中的x, y就是readonly，代表它們只能在建構時指定，事後不得變更。而我原本的寫法. Putting readonly="false" won't work. That enables the compiler to save. GetHashCode used in CoreFX. 2 provides two kinds of code inspections: 259 inspections that detect errors such as broken syntax, unresolved symbols, compiler errors, and so on (you cannot configure or disable any of these inspections), and 267 proprietary code inspections, any of which you can disable or change its severity level. relations. Let’s call B the number of buckets, and H the hash code of the key. GetHashCode() * this. Adds a span of bytes to the hash code. Firstly, I would suggest making the name and lname field. According to the guideline from the question, the hashcode of B would not change. IndexOf members, the code. By default it does it based on the reference to the object, but that means that it's the exact same object, so both would return the same hash. No auto. Sort a List<T> by object property in C#; Parse command line arguments in C#. Suggestions cannot be applied while the C# – Non-readonly fields referenced in GetHashCode () . Non-nullable reference types' default values VS non-nullable value types' default values in C#; Non-nullable string type, how to use with Asp. 18. 3 introduced features that help passing or returning struct by "readonly" reference. To make sure it points to the same place in the memory. Although ReSharper knows about all these warnings and provides design-time notifications for them. 2. The methods part unrolled is:Add this suggestion to a batch that can be applied as a single commit. Gets an empty ReadOnlyDictionary<TKey,TValue>. However, this is only an ideal-situation guideline; the actual rule is: Rule: The integer returned. Share. Name = name; } public String Name { get; private set; } } But that wouldn't allow him to do p. It doesn't matter what value you put after it or if you put any value after it, it will still see it as readonly. This is because the GetHashCode() method is used. The <code>readonly</code> keyword enforces that another instance can’t be assigned to the field, but it cannot keep the contents from being updated. Combines five values into a hash code. Thus I come up with: Public Overrides Function GetHashCode () As Int32 Dim hash As Int32 = 17 hash = hash * 23 + _Name. NET Framework 64-bit version of string. Alternatives. It seems to me that all most answers here were sidetracked into talking about immutability or hashcode guarantees, instead of answering the original question. Add this suggestion to a batch that can be applied as a single commit. Is there a naming convention for the type parameter in generic typed code (bracy flavoured) Apr 1, 2014. readonly will never cover all use cases solely because of the fact that it does not handle runtime immutability. Non-readonly field referenced in GetHashcode. That way Dictionary and HashSet still works, but it will be the worst time complexity for. Net Core options; Non-read only alternative to anonymous types in C#; Non-readonly fields referenced in GetHashCode() in C#; NonSerialized on property in C#; Non-static method requires a target C#Code Inspection: Non-readonly type member referenced in 'GetHashCode()' You can suppress this inspection to ignore specific issues, change its severity level to make the issues less or more noticeable, or disable it altogether. Id is a primitive value, ie. NET Framework 4. Therefore, readonly fields can have different values depending on the constructor used. You can suppress this inspection to ignore specific issues, change its severity level to make the issues less or more noticeable, or disable it altogether. To compute a hash code using the elements of an array, you can cast the array to IStructuralEquatable and then call the GetHashCode (IEqualityComparer) method, passing a comparer for the type of elements in the array. NET, JetBrains Rider 2023. The first Assert ensures that the string is zero-terminated as it should be, required to allow the optimization in the loop. However, if two objects do not compare as equal, the GetHashCode. If the Type. 0, readonly), optionally (except for readonly properties), as of PHP 7. The property system's primary function is to compute the values of properties, and to provide system notification about values that have changed. If a add a non readonly property to the class (e. hence it's best to depend only on readonly fields in your GetHashCode method. Code Inspection: Nullable attribute usage with declaration having value or void type 1. Component is the default implementation of IComponent and serves as the base class for all components in the common language runtime. Implementing IEquatable<T> for a value type is a little bit different than for a reference type. NET don't override Equals or GetHashCode, so the value you'll get is basically based on reference equality (i. the object was being used as a key to a dictionary when it changed) the problem was with either the change or the fact that it's being used for non-reference equality in the first place, not the fact that the value returned by GetHashCode() changed. Within each of the static/non-static groups of fields, order by readonly, then non-readonly : (SA1214 and SA1215) readonly; non-readonly; An unrolled list is 130 lines long, so I won't unroll it here. g. GetHashCode(T) Describe suggestions on how to achieve the rule. set_Prop is the function that implements the setter. Not all form elements can be set to readonly, for example:. In the end, I will show a small. If a non-readonly field is changed after the object is. This leaves the list of applicable members for a GetHashCode() implementation to: Readonly fields; And getter-only properties; That are immutable structs Non-readonly field referenced in 'GetHashCode()' Cannot resolve symbol in text argument; Parameter hides member; Possible 'System. Suggested is to use the W3C standard, which is readonly="readonly". 1 Answer. Now when 2nd object is inserted, once again it call GetHashCode and is compared with all the existing Keys hasCode if it matches It calls Equals override which. The implementation of equality methods (that is Equals() and GetHashCode()) as well as equality operators (that is == and !=) in the Object class guarantees reference equality. This differs from a constant declared with the const modifier, which must have its value set at compile time. Suggestions cannot be applied while theThe reason is that int cannot possibly be null, so any sort of indication that it is or is not null is redundant and can be removed. lname. The out modifier is the same as ref modifier plus the compiler checks for definite assignment. you may have better luck searching for c# info since. This is where with keyword steps in. ShowStringHashCode () ' Create a new app domain and show string hash code. You can learn more about the process for merging feature speclets into the C# language standard in the article on the specifications. . This feature allows you to indicate that an individual method on a non-readonly struct is itself "readonly" (i. Non-readonly fields referenced in GetHashCode () 2021-6-9 anglehua. resharper_not_accessed_positional_property_local_highlighting. Comment actions Think I figured it out. GetHashCode Xor m_Y. You can make the strings on Foo readonly and it should be at that point. GetHashCode reference in MSDN: The default implementation of the GetHashCode method does not guarantee unique return values for different objects. In these scenarios the notion of in-process reference is irrelevant. JetBrains Rider will help you here by pointing at each non-readonly field or non-get-only property in your implementation of GetHashCode(). OrderLineId = orderLineId End Sub Public Overrides Function Equals(obj As. You can use the method from Effective Java as Jon Skeet shows here. When you declare a primary constructor on a record, the compiler. The specification defines that Equals and GetHashcode (note the typo in the specification!) methods will behave for instances of the same type, however the implementation is not defined. Having a read only property to a class object (as opposed to a struct) only prevents modifying the value of the property, in this case the object reference. C# 9. Combines eight values into a hash code. <code>readonly</code> fields can only be assigned in a class constructor. lname = lname; } public override bool. In short, if you need to ensure your property value will never be changed from the outside, but you need to be able to change it from inside your class code, use a "Get-only" property. Would be nice if Resharper were smart en. Alternatives. Data. This rule raises an issue when a static readonly field is initialized with a value that is computable at compile time. hash == y. Gets the dictionary that is wrapped by this ReadOnlyDictionary<TKey,TValue> object. string, int, long, Guid etc. Add this suggestion to a batch that can be applied as a single commit. resharper_nullness_annotation_conflict_with_jet_brains_annotations_highlighting. This suggestion is invalid because no changes were made to the code. Then again, I rarely find myself needing to implement IDisposable. Overriding GetHashCode () for value objects without fields. . In the yml-file the property is defined as readonly: properties: Name: type: string readOnly: true description: Descriptive name of the project the code generated for the property is: public string Uri { get; set; } in browser, if you click on schemas, the property is not marked as readonly. Adds a single value to the hash code, specifying the type that provides the hash code function. The default instance of the EqualityComparer<T> class for type T. The xor operator is commutative, so the ordering is irrelevant. C# 9. non-readonly fields, properties with setters, etc. Adds a span of bytes to the hash code. For fields that hold a mutable reference type, the read-only modifier prevents the field value from being overwritten but does not protect the mutable type from modification. " and the one for ValueType says "If you call the derived type's GetHashCode method, the return value is not likely to be suitable for use as a key in a hash table. get_Prop set_Prop ToString Equals GetHashCode GetType get_Prop is the function that implements the getter. The recommended method for a true readonly property is to omit the setter. Property assignments should not be made for "readonly" fields not constrained to reference types BugFlags enumerations should explicitly initialize all their members Bug"GetHashCode" should not reference mutable fields BugResults of integer division should not be assigned to floating point variables BugSystem. Local. – xanatos. I would expect True. One way is to just keep accumulating and multiplying by 17 like I've done. 1/2. Assembly. public struct ObjectHandle : IEquatable<ObjectHandle> { public object Object; public bool Equals (ObjectHandle. resharper_non_readonly_member_in_get_hash_code_highlighting. Q&A for work. I always made a wrong assumption between the concept of GetHashCode and a "MD5 hash" of a downloaded file. –The VS2005 documentation Guidelines for Overloading Equals() and Operator == (C# Programming Guide) states in part. @sharwell I see you went with the solution of not offering MakeFieldReadonly, when the struct has any mutable fields. net-4. The loop is unrolled by hand, consuming 4 characters per loop for the 32-bit. But a hash should be based on the value, like in the case of the string class. C# 10 allows the record class syntax as a synonym to clarify a reference type, and record struct to define a value type with similar functionality. GetHashCode Xor m_Y. They may be referred to using other terms such as fields, but for the purposes of this reference properties will be used. GetHashCode(). Implementers are encouraged to extend this base class instead of creating their own. Aug 29, 2013 at 9:10. Can someone explain this inspection warning? I did a search on it, and came up empty. Combines six values into a hash code. Non-accessed positional property (non-private accessibility). Stack Overflow | The World’s Largest Online Community for DevelopersIf you're on C# 7, you should consider using value tuples as your composite key. If you love a cozy, comedic mystery, you'll love this 'whodunit' adventure. Equals (b) is true, a. Collections. Generic Interface inheriting Non-Generic One C#; WPF ContextMenu itemtemplate, menuitem inside menuitem; Pass values of checkBox to controller action in asp. DateTime (2011,06,04) should equal DateTime (2011,06,04). The factory could maintain a collection of all of the objects created using weak references. Notes to Implementers. if <TKey> is of custom type you should care about implementing GetHashCode () carefully. A class that overrides only one of Equals(object) and GetHashCode() is likely to violate the contract of the GetHashCode() method. The readonly keyword is used to declare a member variable a constant, but allows the value to be calculated at runtime. Hashtable. Override Object. @DeniseSkidmore If you try to call GetHashCode on null you'll get a null reference exception. However there are two limitations which apply to your Id property. That not only misses some scenarios where the field could be converted to readonly even though its mutable (if there are no writes and no invocations), but it is also wrong, as you can see in the example. >) since value tuples are value types (structs), not reference types, so they avoid the memory allocation and garbage collection costs. Gets the element that has the specified key. Remarks. GetHashCode(), use. Add this suggestion to a batch that can be applied as a single commit. private readonly int. GetHashCode (); } Once you have this method in place, then use the comparer in your call to Except. This could be supported today by an analyzer. For information about ref struct and readonly ref struct types, see the ref structure types article. This attribute allows a field value to be set in the constructor of the same class. html; string. Value types must override this method to provide a hash function that is appropriate for that type and to provide a useful distribution in a hash table. In the Properties window, ensure that the "Copy to Output Directory" property is set to "Copy always" or "Copy if newer". internal class Person { public string name; public int age; public string lname; public Person (string name, int age, string lname) { this. GetHashCode () implemented like it is?, the default behaviour of GetHashCode for value types, which struct is, is to return hash based on the values. name. The Equals method is used to compare two key values. The result of this would be: A. You use the record modifier to define a reference type that provides built-in functionality for encapsulating data. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. You don't need the empty constructor anymore - EF Core will be able to use the constructor with Guid id parameter. net string class immutability asked Dec 23, 2013 at. If you need to be able to set the property just once then define the set as private and pass the parameter into the constructor: public class Person { public Person (String name) { this. ToString and Equals are likely common methods that would be good to mark as readonly. GetHashCode() * this. –1. MachineName property open System // <-- Keep this information secure! --> printfn $" MachineName: {Environment. For the best performance, a hash function must generate a random distribution for all input. Research Branch Staff Publications Biodiversity guidebook - Forest Practices Code of British Columbia. Creating a comparer class for your type is an alternative to creating Equals() and GetHashCode() methods for the type. Description. Collections. Is it possible in MVC 3 to set a ReadOnly Attribute to true or false on Model depending of a property in the same class? maybe something like : ReadOnly ( (yyy)?false:true) public double? xxx { get; set; } I need to do it in the model or in the controller. returns true. age. To avoid any problem you should make sure that the static field csvSeparator field is only assigned by the class constructor method of your class. You can suppress this inspection to ignore specific issues, change its severity level to make the issues less or more noticeable, or disable it altogether. To a certain extent, they are. Don't let them initialize by themselves. Thus I come up with: Public Overrides Function GetHashCode () As Int32 Dim hash As Int32 = 17 hash = hash * 23 + _Name. ValueType defines its own rules for generating hash codes by overriding System. If an. As far as I know, the purpose of unit tests is to verify, whether method works as it is documented. At the time of insertion of your object your GetHashCode() returned some value and that object got inserted into some bucket. NET Core 2. Only implement IEquatable<T> for structs or sealed classes. Warning. ToLower() and string. The second. public struct Complex { public double RealPart { get; set; } public double ImaginaryPart { get;. protected virtual bool HandleTextInput(string text) Parameters. In VB. AllowedItem'. Warning. Declaration. And be very careful to meet all the requirements for those methods. Resolution: I'm marking JaredPar as accepted, but mainly for the comments interaction. Finally, there is an explicit statement in object. C# 10 allows the record class syntax as a synonym to clarify a reference type, and record struct to define a value type with similar functionality. However, when you access the property you get a reference to your internal HashTable object, and you are free to call any public method on the HashTable object returned,. Non-readonly fields referenced in GetHashCode() in C#; ASP. 7. ReSharper will help you here by pointing at each non-readonly field or non-get-only property in your implementation of GetHashCode(). Reversed. GetHashCode () // Calculate the index of the. This suggestion is invalid because no changes were made to the code. RuntimeHelpers. Runtime. Two objects that are equal return hash codes that are equal. Any subsequent test to see if the object is in the Hashtable will return a false negative. C++ Pointers and References; Python - Random range in list; Python - Modulo K elements removal;. An override of Object. Select one or more items in the Solution Explorer to make fields readonly in the files under these nodes and their child items. The general principle is to place entries in a fixed number of “buckets”, according to the hash code of the key. // Sample for the Environment. e. This feature could be confused with immutable types which aim to enforce deep immutability but is much stricter in that every field must also be of an immutable type. Non-readonly fields referenced in GetHashCode() in C#; How to train multiple models in a single script in TensorFlow when there are GPUs present? Flatten list of lists in python; How does asyncio actually work? Dropping infinite values from dataframes in pandas? Sort dataframe by string length in python; Where is the history file for ipythonJava 8 introduced a new feature into HashMap whereby when a significant number of keys fall into the hash bucket and the key type implements Comparable<T> (broadly equivalent to . Add this suggestion to a batch that can be applied as a single commit. Suggestions came in this line of code:. In C#, it is generally not recommended to reference non-readonly fields in the GetHashCode() method of a class. However, when you access the property you get a reference to your internal HashTable object, and you are free to call any public method on the HashTable object returned, including adding. Class member variables are called properties. It provides a detailed trace of the sequence of method calls that led to the exception being thrown, along with the file name and line number where each method call occurred. 推荐答案. NullReferenceException' Possible unintended reference comparison; Return value of pure method is not used Non-readonly type member referenced in 'GetHashCode()' resharper_non_readonly_member_in_get_hash_code_highlighting. GetHashCode so that two objects that have value equality produce the same. The struct remains a struct. MachineName property open System // <-- Keep this information secure! --> printfn $" MachineName: {Environment. Combines four values into a hash code. Property getters are likely the other common case where there will be no. 1. Introduction. The text from the corresponding TextCompositionEventArgs. And identifiers fit well with the value-based equality described above. The hash code is not required to be unique or collision resistant for correctness. For example, the implementation of the GetHashCode method provided by the String class returns identical hash codes for identical string values. And if you can just use reference equality (when you'd never have two different instances of your class that can be equal) then you can safely use Equals and GetHashCode that are inherited from Object. Concurrent/src/System/Collections/Concurrent":{"items":[{"name. 1 introduced Entity types with constructors with parameters feature. Examples. Collections. GetHashCode() * this. 16. No, the stack trace of an exception in C# can never be null. This is because the GetHashCode () method is used to generate a hash code for the object, which is used in hashing algorithms and data structures like dictionaries and sets. Today, we will do the same thing for value types, which are far more complex due to their representation in memory. Two objects that are the same type and are equal must return the same hash code to ensure that instances of the following types work correctly: System. A readonly field can be assigned multiple times in the field declaration and in any constructor. This means the properties of the constructed type cannot be reassigned. forEach ( (key: keyof Options) => { // This is not allowed (error: Cannot assign to '. The example below shows that even if a field is assigned non-constant value and has no read usages, ReSharper will help you detect the unused member. 至于 age，这是定期变化的东西，所以最好存储一个. NET Libraries. A record uses properties though, not raw fields, so you can only compare structs with properties to record structs. The C# documentation states [1]: If two objects compare as equal, the GetHashCode method for each object must return the same value. Warning. #pragma warning disable RECS0017 // Possible compare of value type with 'null' #pragma warning disable RECS0025 // Non-readonly field referenced in 'GetHashCode()' using System. Here at NDepend we enjoy so much immutable types that several rules help enforce this property: Fields should be marked as ReadOnly when. This can lead to unexpected behavior when using GetHashCode, as it will return different values for two objects that are logically equivalent but have different. "The GetHashCode method can be overridden by a derived type. Although ReSharper knows about all these warnings and provides design-time notifications for. Contribute to icsharpcode/RefactoringEssentials development by creating an account on GitHub. A collection that is read-only does not allow the addition, removal, or modification of elements after the collection is created. You use the record modifier to define a reference type that provides built-in functionality for encapsulating data. If GetHashCode uses non- readonly fields and those fields change after the object is stored, the object. This is because the GetHashCode () method is. Example In the following example, two properties are created. Not enforcing this property may cause unexpected results when. Thus, there are some good practices to follow to avoid problems related to thread synchronization. ); or. For information about the service packs and cumulative update list for BizTalk Server, see KB 2555976: Service pack and cumulative update list for BizTalk Server. Property assignments should not be made for "readonly" fields not constrained to reference types BugFlags enumerations should explicitly initialize all their members Bug"GetHashCode" should not reference mutable fields BugResults of integer division should not be assigned to floating point variables BugWhy is this an issue? Making a base call when overriding a method is generally a good idea, but not in the case of GetHashCode and Equals for classes that directly extend Object. You've lost the forest for the trees, friend. These seem naturally contradicting when a mutable object, because if the state of the object changes. 2; Using an array in Azure web app settingsSorted by: 4. Equals (projection (t2)); hashFunction = t => projection (t). Code Inspection: Non-readonly type member referenced in 'GetHashCode()' You can suppress this inspection to ignore specific issues, change its severity level to make the issues less or more noticeable, or disable it altogether. we use Process. But, remember - records are immutable. Also, they offer conciser and. hash. Collections. Avoid using reference equality in your implementation of Equals. CS0169: Private field is never used. If that causes problems (e. . Having a read only property to a class object (as opposed to a struct) only prevents modifying the value of the property, in this case the object reference. MSDN documentation of the GetHashCode() method does not explicitly require that your override of this method. Add this suggestion to a batch that can be applied as a single commit. Records (C# reference) C# record types offer: read-only properties, which makes an instance of the type immutable without additional work such as defining fields or properties with specific keywords. By default, EF Core uses the. itoolpad. Public Structure OrderOrderLine Implements IEquatable(Of OrderOrderLine) Public ReadOnly Property OrderId As Integer Public ReadOnly Property OrderLineId As Integer Public Sub New(ByVal orderId As Integer, ByVal orderLineId As Integer) Me. GetHashCode to find the hash code, then for all. xxx) in the view. The stack trace is an important piece of information that is automatically generated when an exception is thrown. private readonly string _widgetName = GetWidgetName (); public string WidgetName { get { return _widgetName; } } So, the value is stored in _widgetName and it's safe because it's readonly, and you can't change it's value as before. For the comparison you can use the SetEquals. Try this comparer:Call to a non-readonly member from a 'readonly' member results in an implicit copy of 'this' CSharpWarnings::CS8656. It facilitates the integration of the following types of information:A suspicious death, an upscale spiritual retreat, and a quartet of suspects with a motive for murder. Refactoring Essentials for Visual Studio. Otherwise, the method is virtual and protected. In general, for mutable reference types, you should override GetHashCode only if: You can compute the hash code from fields that are not mutable; or You can ensure that the hash code of a mutable object does not change while the object is contained in a collection that relies on its hash code. This is know as the "once" feature in Eiffel.