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TypeHelper

Namespace: SnowBank.Runtime · class

Extensions methods that add advanced features on Type

Methods

CanAssignNull

static bool CanAssignNull(Type type)

Tests if an instance of type can be null (Reference Type, Nullable Type)

CompileGenerator

static Func<object> CompileGenerator(Type type)

Generates a factory method that will instantiate an object of the specified type, or equivalent, if possible

  • type — Type of the object to instantiate (can be an interface or abstract class, for a limited set of "well known" types)

Returns: Function that calls the parameterless constructor for the type, or null if it is impossible to create such a type (unsupported interface or abstract class, type without a parameterless ctor, ...)

CompileGetter

static Func<object, object> CompileGetter(FieldInfo field)

Generates a getter Lambda (object instance) => (object) ((TInstance) instance).FIELD

static Func<object, object> CompileGetter(PropertyInfo property, bool nonPublic = false)

Generates a getter Lambda (object instance) => (object) ((TInstance) instance).PROPERTY

Set to also use a non-public get accessor (compiled expression trees can invoke them)

CompileSetter

static Action<object, object> CompileSetter(FieldInfo field)

Generates a setter Lambda (object instance, object value) => ((TInstance) instance).FIELD = (TValue) value

Returns: Returns null if the field is read-only

static Action<object, object> CompileSetter(PropertyInfo property, bool nonPublic = false)

Generates a setter Lambda (object instance, object value) => ((TInstance) instance).PROPERTY = (TValue) value

Returns: Returns null if the property is read-only

Set to also use a non-public set accessor (compiled expression trees can invoke them)

ConvertKeyToString

static string ConvertKeyToString(object key)

Converts an arbitrary dictionary key to a string literal, that can be used as a key in a string-only map (such as the field name in a JSON Object)

  • key — Instance that represents a key

Returns: Corresponding string literal

FindGenericType

static Type FindGenericType(Type type, Type genericType)

Returns the closed version of the generic interface implemented by a type

  • type — Type of the inspected instance (ex: List)
  • genericType — Type of the generic interface (ex: IList<>)

Returns: Closed interface (ex: IList), or null if the type does not implement this generic interface

GetAssemblyName

static string GetAssemblyName(Type type)

Returns the full name of a type, that can be later passed to Type.GetType(...) to retrieve the original type

  • type — Type

Returns: Name of the type, with the form "Namespace.ClassName, AssemblyName"

GetCompilableTypeName

static string GetCompilableTypeName(Type type, bool omitNamespace, bool global)

Returns a "human-readable" version of a type's name, including the generic arguments and nested types.

Returns: "string", "int", "FooBar", "FooBar.NestedBaz", "List", "Dictionary<string, Something<Foo, Bar>>"

This name will NOT be in a format that easily allows retrieve it later, and should mostly be used in error message, logs or debug messages.

GetDefaultValue

static object GetDefaultValue(Type type)

Returns the default value for a type

Returns: null, 0, false, DateTime.MinValue, ...

GetFriendlyName

static string GetFriendlyName(Type type)

Returns a "human-readable" version of a type's name, including the generic arguments and nested types.

Returns: "string", "int", "FooBar", "FooBar.NestedBaz", "List", "Dictionary<string, Something<Foo, Bar>>"

This name will NOT be in a format that easily allows retrieve it later, and should mostly be used in error message, logs or debug messages.

static string GetFriendlyName(MethodBase method, bool omitNamespace = true)

Returns a "human-readable" version of a method's name, including the parameters.

Returns: "

GetTaskLikeType

static Type GetTaskLikeType(Type taskLike)

Returns the type returned by a 'Task-like' type (Task, Task>T<, ValueTask<T>, ...), or null if it is not a task.

IsAnonymousType

static bool IsAnonymousType(Type type)

Tests if a type is an anonymous type generated by the compiler (ie: new { foo = ..., bar = .... })

IsAssignableTo

static bool IsAssignableTo<T>(Type type)

Tests if a type is in instance of another type, abstract class, or interface

  • type — Type of the instance

Returns: true if an instance of type type can be assigned to a variable of type T

IsConcrete

static bool IsConcrete(Type type)

Tests if a type is "concrete", meaning it is not a class or struct that is not abstract

  • type — Type to inspect

Returns: false if the type is an interface an abstract class, or Object; otherwise, true

This includes both sealed class, and non-sealed but non-abstract class.

IsConcreteImplementationOfInterface

static bool IsConcreteImplementationOfInterface(Type type, Type interfaceType)

Tests if a type is a concrete implementation of a specific interface

Returns: false if the type does not implement this interface, is an itself an interface, an abstract class, or Object; otherwise, true

IsCustomIndexer

static bool IsCustomIndexer(PropertyInfo prop)

Tests if a property is a custom indexer (ex: "get_Item[string key]")

IsDictionaryType

static bool IsDictionaryType(Type type, out Type keyType, out Type valueType)

Tests if a type implements IDictionary and returns the types of the keys and values when this is the case

  • type — Type of the inspected instance (ex: List<string>)
  • keyType — When the method returns true, receives the types of the keys
  • valueType — When the method returns true, receives the types of the values

Returns: true if the type implements IDictionary; otherwise, false.

typeof(Dictionary<int, string>).IsDictionaryType(out var keyType, out var valueType) == true; keyType == typeof(int); valueType == typeof(string)
typeof(List<KeyValuePair<int, string>>).IsDictionaryType(...) == false

IsEnumerableType

static bool IsEnumerableType(Type type, out Type elementType)

Tests if a type implements IEnumerable and returns the type of the enumerated elements when this is the case

  • type — Type of the inspected instance (ex: List<string>)
  • elementType — When the method returns true, receives the types of the enumerated elements

Returns: true if the type implements IEnumerable; otherwise, false.

typeof(List<string>).IsEnumerableType(out var elementType) == true; elementType == typeof(string)
typeof(Dictionary<int, string>).IsEnumerableType(out var elementType) == true; elementType == typeof(KeyValuePair<int, string>)
typeof(string).IsEnumerableType(out var elementType) == true; elementType == typeof(char)
typeof(int).IsEnumerableType(out var elementType) == false;

IsGenericInstanceOf

static bool IsGenericInstanceOf(Type type, Type genericType)

Tests if a type is implements a generic type or interface

  • type — Type of the inspected instance (ex: List<string>)
  • genericType — Type of the generic interface (ex: IList<T>)

Returns: true if the type implements the generic interface

This method is required because new List().GetType().IsAssignableTo(IList<>) returns false (the types implements IList which is not the same as IList<>)

typeof(List<string>).IsGenericInstanceOf(typeof(IList<>)) == true
typeof(HashSet<string>).IsGenericInstanceOf(typeof(IList<>)) == false

static bool IsGenericInstanceOf(Type type, Type genericType, out Type closedType)

Tests if a type is implements a generic type or interface

  • type — Type of the inspected instance (ex: List<string>)
  • genericType — Type of the generic interface (ex: IList<>)
  • closedType — Receives the corresponding closed generic type (ex: IList<string>)

Returns: true if the type implements the generic interface

This method is required because new List().GetType().IsAssignableTo(IList<>) returns false (the types implements IList which is not the same as IList<>)

typeof(List<string>).IsGenericInstanceOf(typeof(IList<>), out var closedType) == true && closedType == typeof(IList<string>)
typeof(HashSet<string>).IsGenericInstanceOf(typeof(IList<>)) == false

IsNullableType

static bool IsNullableType(Type type)

Tests if a type is nullable (ie: 'int?' or 'DateTime?')

IsSameGenericType

static bool IsSameGenericType(Type type, Type genericType)

Tests if a generic type has the same generic definition as another type (ie: Dictionary<string, int> ~= Dictionary<,>

  • type — Type to inspect (ex: IDictionary<string, string>)
  • genericType — Generic type (ex: IDictionary<,>)

Returns: true if the types are equivalent; otherwise, false.

MakeGenericMethod

static MethodInfo MakeGenericMethod(Type type, string name, BindingFlags flags, params Type[] types)

Returns the generic version of a method

  • type — Declaring type
  • name — Name of the method
  • flags — Binding flags
  • types — Types of the generic arguments of the method

Returns: Corresponding generic method

TryGetCustomAttribute

static bool TryGetCustomAttribute(MemberInfo member, string attributeName, bool inherit, out Attribute attribute)

Returns an Attribute of a member of a type, given its name

  • member — Member (field or property)
  • attributeName — Name (without the namespace) of the attribute to fetch (ex: "DataMemberAttribute")
  • inherit — true to also look into the attributes up the derived chain
  • attribute — receives the corresponding Attribute if found; otherwise, null

Returns: true if the attribute was found; otherwise, false.