• Avalanche
  • Avalanche.Core
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    • Avalanche.Localization
      • Introduction
      • Localization
      • LocalizationFile
      • LocalizationFiles
      • LocalizationFileSystem
      • LocalizationFileFormat
      • LocalizationLine
      • LocalizationLines
      • TemplateFormat
      • CultureProvider
      • FallbackCultureProvider
      • ResourceManager
      • LocalizationError
      • Microsoft.Extensions
        • Introduction
        • DependencyInjection
        • FileProvider
        • Logging
        • ITextLocalizer
        • IFileLocalizer
        • Localization
        • AspNetCore
      • Pluralization
        • Introduction
        • Multiple plural parameters
        • Custom PluralRules
        • Invariant Culture
        • Unit Prefix
        • IPluralRule
        • IPluralNumber
        • IPluralRules
        • CLDRs
        • Unicode.CLDR41
        • Unicode.CLDR40
      • Articles
        • Alphabet localization
        • Benchmarks
        • Caching
        • Class Library
        • Demo
        • Diagnostics
        • Embedded resources
        • Emplacement
        • File localization
        • Text localization
    • Avalanche.Message
      • Introduction
      • IMessage
      • IMessageProvider
      • IMessageDescription
      • IMessageDescriptions
      • MessageLevel
      • Message printing
      • Messages and Exceptions
      • Logging
      • Validation
      • Localization
    • Avalanche.StatusCode
      • Introduction
      • HResult
        • Introduction
        • HResult.Facilities
        • BasicMessages
        • RpcMessages
        • DispatchMessages
        • ItfMessages
        • Win32Messages
        • ClrMessages
      • System
        • Introduction
        • AccessControlMessages
        • AggregateMessages
        • AppDomainMessages
        • ArgumentMessages
        • ArgumentNullMessages
        • ArgumentOutOfRangeMessages
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        • InvalidCastMessages
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        • IsolatedStorageMessages
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        • MemoryMessages
        • MiscellaneousMessages
        • NotImplementedMessages
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        • ObjectDisposedMessages
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        • OverflowMessages
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        • TimeZoneMessages
        • TypeMessages
        • XmlMessages
    • Avalanche.Template
      • Introduction
      • TemplateFormats
      • ITemplatePrintable
      • ITemplateFormatPrintable
      • ITemplateText
      • ITemplateBreakdown
      • ITemplateFormat
      • ITemplateFormats
      • Extract Arguments
      • Emplacement
    • Avalanche.Tokenizer
      • Introduction
      • IToken
      • ITokenizer
      • Tokenizers
    • Avalanche.Service
      • Introduction
      • Service
        • IService
        • Construction
        • Query
        • CancellationToken
        • CachePolicy
        • Cast
        • Scope
        • Dispose
      • Handler
        • Introduction
        • IHandler
        • Cancel
        • Recursion
        • Cyclicity
        • Delegates
        • Casting
        • Invokable
        • Handlers
      • Request
        • Introduction
        • IRequest
        • [Request]
        • [ContextParameter]
        • Print Tree
      • Dependency Injection
        • Introduction
        • ServiceRequest<T>
        • Handler
        • CachePolicy
        • CancellationToken
        • QueryLogger
      • Examples
        • Expression Example
        • Mapper Example
      • ServiceMessages
    • Avalanche.Writer
      • Introduction
      • Writer
      • Referer
      • TypeCast
      • DefaultConstructor
      • DelegateWriter
      • WriterPipe
      • ConstantWriter
      • PassthroughWriter
      • Context
      • WriterMessages
    • Avalanche.Accessor
      • Introduction
      • AccessorServices
      • List
        • ListAccessor
        • ListConstructor
        • ListDeconstructor
        • ListDefaultConstructor
        • ListGet
        • ListSet
        • ListAdd
        • ListInsert
        • ListClear
        • ListCount
        • ListIndexOf
        • ListRemoveAt
        • ListReferer
      • Map
        • MapAccessor
        • MapConstructor
        • MapDeconstructor
        • MapDefaultConstructor
        • MapSet
        • MapGet
        • MapRemove
        • MapClear
        • MapCount
        • MapReferer
      • Record
        • RecordAccessor
        • RecordConstructor
        • RecordDeconstructor
        • RecordDefaultConstructor
      • Field
        • FieldAccessor
        • FieldReader
        • FieldWriter
        • FieldReferer
      • Dependency Injection
        • Introduction
      • AccessorMessages
    • Avalanche.Emit
      • Introduction
      • TypeBuilder
      • ConstructorBuilder
      • MethodBuilder
      • PropertyBuilder
      • FieldBuilder
      • Emit
      • Utilities
    • Avalanche.DataType
      • Introduction
      • IDataTypeBase
      • IDataType
      • IRecordType
      • IFieldType
      • IUnionType
      • IListType
      • IMapType
      • IValueType
      • IEnumerationType
      • IIntegerType
      • IRealType
      • IStringType
      • IAnyType
      • DataTypeRequest
      • PrintTree
      • DataTypeMessages
    • Avalanche.FileSystem
      • Introduction
      • Abstractions
        • IFileSystem
          • IFileSystemBrowse
          • IFileSystemCreateDirectory
          • IFileSystemDelete
          • IFileSystemFileAttribute
          • IFileSystemMount
          • IFileSystemMove
          • IFileSystemObserve
          • IFileSystemOpen
        • IEvent
        • IEntry
        • IOption
        • IToken
      • FileSystem
      • VirtualFileSystem
      • MemoryFileSystem
      • EmbeddedFileSystem
      • HttpFileSystem
      • Decoration
      • IFileProvider
      • Events
      • Utilities
        • Dispose
        • File Scanner
        • Visit Tree
        • File Operation
    • Avalanche.Identity
      • Introduction
      • Identity
      • IdentityParts
      • IdentityInterner
      • IdentityComparer
      • Print Tree
      • IdentityAccessors
        • Introduction
        • TypeName
    • Avalanche.Utilities
      • Introduction
      • Collections
        • Tuples
        • StructList
        • ArrayList
        • BijectionMap
        • LocakableDictionary
        • LockableList
        • MapList
        • Pipe
        • RingQueue
        • EnumerableExtensions
        • TupleUtilities
        • ArrayUtilities
      • Comparers
        • IGraphComparer
        • IGraphComparable
        • AlphaNumericComparer
        • EnumerableComparer
        • EnumerableGraphComparer
        • ReferenceComparer
        • KeyValuePairComparer
        • DefaultComparerProvider
        • RecordComparer
      • Cloners
        • ICloner
        • IGraphCloner
        • IGraphCloneable
        • EnumerableCloner
        • FieldCloner
        • PassthroughCloner
        • RecordCloner
        • ClonerProvider
      • Dispose
        • IDisposeAttachable
        • IDisposeBelatable
      • Provider
        • Introduction
        • ProviderBase
        • Delegate
        • Concatenation
        • Cache
        • ResultCapture
        • AsReadOnly
        • AsService
      • Record
        • IRecordDescription
        • IFieldDescription
        • IConstructorDescription
        • IConstructionDescription
        • IParameterDescription
        • IRecordProviders
        • RecordDelegates
          • RecordCreate
          • RecordClone
          • RecordCopy
          • IRecordDelegates
        • FieldDelegates
          • FieldRead
          • FieldWrite
          • RecreateWith
          • IFieldDelegates
      • String
        • IEscaper
        • UnicodeString
      • Miscellaneous
        • IIdGenerator
        • Permutation
        • IReadOnly
        • IUserDataContainer
        • Void
    • Avalanche.Core
      • License
      • Order

    FieldReferer

    Field referer is an IRefererBase<Record, Field> that returns pointer to a field.

    IReferer<MyClass, int> myClassIdReferer;
    IRefererFromRef<MyStruct, int> myStructIdReferer;
    

    Creating a referer

    A simple referer implements just IWriterToRef<record,Field>.

    IReferer<MyClass, int> myClassIdReferer = new MyClassIdReferer();
    IRefererFromRef<MyStruct, int> myStructIdReferer = new MyStructIdReferer();
    
    /// <summary></summary>
    public class MyClassIdReferer : IReferer<MyClass, int>
    {
        public bool CanRefer => true;
        public Type FromType => typeof(MyClass);
        public Type ToType => typeof(int);
        public ref int GetReference(MyClass record, IServiceProvider? context = null) => ref record.Id;
        public bool Accept(IWriterVisitorBase visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererT: this);
    }
    
    /// <summary></summary>
    public class MyStructIdReferer : IRefererFromRef<MyStruct, int>
    {
        public bool CanRefer => true;
        public Type FromType => typeof(MyStruct);
        public Type ToType => typeof(int);
        public ref int GetReference(ref MyStruct record, IServiceProvider? context = null) => ref record.Id;
        public bool Accept(IWriterVisitorBase visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererTFR: this);
    }
    

    FieldRefererRequest(IFieldDescription) builds a referer from field description.

    FieldInfo fi = typeof(MyClass).GetField("Id")!;
    IFieldDescription fieldDescription = new FieldDescription().Read(fi).SetReadOnly();
    FieldRefererRequest request = new FieldRefererRequest(fieldDescription);
    IRefererBase<MyClass, int> myClassIdReferer = AccessorServices.Instance.GetRequired<FieldRefererRequest, IRefererBase<MyClass, int>>(request);
    

    Usage

    Referer get pointer to a field of a record.

    MyClass myClass = new MyClass(6, "");
    ref int id = ref myClassIdReferer.GetReference(myClass);
    MyStruct myStruct = new MyStruct(7, "");
    ref int id2 = ref myStructIdReferer.GetReference(ref myStruct);
    

    Custom referer builder

    Custom handler can front-run FieldRefererRequest request.

    public class MyClassIdRefererBuilder : IHandler<FieldRefererRequest, IWriterBase>
    {
        [Order(-100)]
        public void Handle(IQuery<FieldRefererRequest, IWriterBase> query)
        {
            // Already handled
            if (query.Handled()) return;
    
            // 
            if (query.Request.Target is not IFieldDescription fieldDescription) return;
            // Get record type
            Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Referer as MemberInfo)?.DeclaringType!;
            // This handler only handles "MyClass"
            if (!typeof(MyClass).Equals(recordType)) return;
            //
            if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
            // Create referer
            IWriterBase referer = new MyClassIdReferer();
            // Assign referer
            query.Response.SetValue(referer);
        }
    }
    
    // Create service
    IService service = Services.Create((AccessorServices.Handlers, new MyClassIdRefererBuilder()), CachePolicies.Default);
    // Create field description
    IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
    // Referer request
    FieldRefererRequest request = new FieldRefererRequest(fieldDescription);
    // Get referer
    IReferer<MyClass, int> myClassIdReferer = service.GetRequired<FieldRefererRequest, IReferer<MyClass, int>>(request);
    // Create class
    MyClass myClass = new MyClass(6, "");
    // Read
    ref int id = ref myClassIdReferer.GetReference(myClass);
    

    Full Example

    Full Example

    Full example

    using System;
    using System.Reflection;
    using Avalanche.Accessor;
    using Avalanche.Service;
    using Avalanche.Utilities;
    using Avalanche.Utilities.Record;
    using Avalanche.Writer;
    
    public class fieldreferer
    {
        // <00>
        public class MyClass
        {
            public int Id;
            public string Label;
    
            public MyClass(int id, string label)
            {
                Id = id;
                Label = label;
            }
        }
    
        public struct MyStruct
        {
            public int Id;
            public string Label;
    
            public MyStruct(int id, string label)
            {
                Id = id;
                Label = label;
            }
        }
        // </00>
    
        public static void Run()
        {
            {
    #pragma warning disable CS0168
                // <01>
                IReferer<MyClass, int> myClassIdReferer;
                IRefererFromRef<MyStruct, int> myStructIdReferer;
                // </01>
    #pragma warning restore CS0168
            }
            {
                // <11>
                //var myClassIdReferer = DelegateWriter.Referer((MyClass record) => record.Id);
                //var myStructIdReferer = DelegateWriter.Referer((MyStruct record) => record.Id);
                // </11>
            }
            {
                // <12>
                IReferer<MyClass, int> myClassIdReferer = new MyClassIdReferer();
                IRefererFromRef<MyStruct, int> myStructIdReferer = new MyStructIdReferer();
                // </12>
            }
    
            {
                // <17>
                FieldInfo fi = typeof(MyClass).GetField("Id")!;
                IFieldDescription fieldDescription = new FieldDescription().Read(fi).SetReadOnly();
                FieldRefererRequest request = new FieldRefererRequest(fieldDescription);
                IRefererBase<MyClass, int> myClassIdReferer = AccessorServices.Instance.GetRequired<FieldRefererRequest, IRefererBase<MyClass, int>>(request);
                // </17>
            }
            {
                FieldInfo fi = typeof(MyStruct).GetField("Id")!;
                IFieldDescription myStructDescription = new FieldDescription().Read(fi).SetReadOnly();
                FieldRefererRequest myStructRequest = new FieldRefererRequest(myStructDescription);
                IRefererBase<MyStruct, int> myStructIdReferer = AccessorServices.Instance.GetRequired<FieldRefererRequest, IRefererBase<MyStruct, int>>(myStructRequest);
            }
    
    
            {
                IReferer<MyClass, int> myClassIdReferer = new MyClassIdReferer();
                IRefererFromRef<MyStruct, int> myStructIdReferer = new MyStructIdReferer();
    
                // <21>
                MyClass myClass = new MyClass(6, "");
                ref int id = ref myClassIdReferer.GetReference(myClass);
                MyStruct myStruct = new MyStruct(7, "");
                ref int id2 = ref myStructIdReferer.GetReference(ref myStruct);
                // </21>
            }
    
            {
                // <32>
                // Create service
                IService service = Services.Create((AccessorServices.Handlers, new MyClassIdRefererBuilder()), CachePolicies.Default);
                // Create field description
                IFieldDescription fieldDescription = new FieldDescription().Read(typeof(MyClass).GetField("Id")!).SetReadOnly();
                // Referer request
                FieldRefererRequest request = new FieldRefererRequest(fieldDescription);
                // Get referer
                IReferer<MyClass, int> myClassIdReferer = service.GetRequired<FieldRefererRequest, IReferer<MyClass, int>>(request);
                // Create class
                MyClass myClass = new MyClass(6, "");
                // Read
                ref int id = ref myClassIdReferer.GetReference(myClass);
                // </32>
            }
        }
    
        // <13>
        /// <summary></summary>
        public class MyClassIdReferer : IReferer<MyClass, int>
        {
            public bool CanRefer => true;
            public Type FromType => typeof(MyClass);
            public Type ToType => typeof(int);
            public ref int GetReference(MyClass record, IServiceProvider? context = null) => ref record.Id;
            public bool Accept(IWriterVisitorBase visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererT: this);
        }
    
        /// <summary></summary>
        public class MyStructIdReferer : IRefererFromRef<MyStruct, int>
        {
            public bool CanRefer => true;
            public Type FromType => typeof(MyStruct);
            public Type ToType => typeof(int);
            public ref int GetReference(ref MyStruct record, IServiceProvider? context = null) => ref record.Id;
            public bool Accept(IWriterVisitorBase visitor) => visitor is not IRefererVisitor v ? true : v.Visit(refererTFR: this);
        }
        // </13>
        // <31>
        public class MyClassIdRefererBuilder : IHandler<FieldRefererRequest, IWriterBase>
        {
            [Order(-100)]
            public void Handle(IQuery<FieldRefererRequest, IWriterBase> query)
            {
                // Already handled
                if (query.Handled()) return;
    
                // 
                if (query.Request.Target is not IFieldDescription fieldDescription) return;
                // Get record type
                Type recordType = fieldDescription.Record?.Type ?? (fieldDescription.Referer as MemberInfo)?.DeclaringType!;
                // This handler only handles "MyClass"
                if (!typeof(MyClass).Equals(recordType)) return;
                //
                if (!"Id".Equals(fieldDescription.Name?.ToString())) return;
                // Create referer
                IWriterBase referer = new MyClassIdReferer();
                // Assign referer
                query.Response.SetValue(referer);
            }
        }
        // </31>
    }
    

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