Geranium.Reflection

.NET reflection provided by ExpressionTrees. An alternative for reflection by extensions methods based on Expressions. This extensions allow create new instances without activator, set or get property values of unknown types and unknown properties, check equality with unknown type default value, call object methods and extension methods avoiding Invoke, and couple of non-expression extensions for as/is.

Benchmarks

Full table available here: Benchmark resuts

New

New() average faster then Activator in 10 times, short info:

Method	Mean	Allocated
New	30.655 ns	72 B
New (params)	72.224 ns	144 B
Activator	558.993 ns	568 B

Get

GetPropValue() average faster then PropertyInfo in 2-5 times

Method	Mean	Allocated
Reflection	103.186 ns	24 B
GetPropValue	17.372 ns	24 B

Set

SetPropValue() average faster then PropertyInfo in 2-5 times

Method	Mean	Allocated
Reflection	118.99 ns	24 B
SetPropValue	32.04 ns	128 B

Short list of features:

New
get/set
default
is
as
call

Supported targets:

net6.0+
netcoreapp3.1+
netstandard2.1+
net46+

New

Alternative for Activator.CreateInstance provided by Expression.New lambda cached by System.Type into Delegate.

Available methods

object New(this object obj)
object New<T1, T2, ..., T16>(this object obj, T1 arg1,T2 arg2,..., T16 arg16)
object New(this object obj, params object[] args)

Examples

Getting List<T> as IList of Type in runtime:

public static IList IList(this Type type)
{
    return typeof(List<>).MakeGenericType(type)
        .New()
        .As<IList>();
}

Create and apply migration from migration type:

void RunMigration(Type migrationType)
{
    var migration = migrationType.New().As<CodegenMigration>();
    ...
    migration.Apply();
    ...
}

Get property / Set property

Get property values:

There is three methods for getting value from property based on Expression.PropertyOrField:

object GetPropValue(this object obj, string propName)
TValue GetPropValue<TValue>(this object obj, string propName)
TValue GetPropValue<THost, TValue>(this THost obj, string propName)

Example of getting 'Id' value of uknown type:

var rowAccess = new RowAccess
{
    Type = typeof(T),
    IdValue = entity.GetPropValue("Id") // value can be long/string/Guid or something
};

Set property values:

There is only one method for setting value:

void SetPropValue(this object obj, string propName, object propValue)

But it can works different based on passed value:

Usually (for nullable too) its just set value by lambda
For enum values it wraps action with Enum.Parse(value.ToString())
If you pass wrong type for value, it will try convert by Convert.ChangeType

Example method of setting 'Id' value when you don't know type:

public static void SetId<TId>(this object obj, TId value) 
=> obj.SetPropValue("Id", value);

public static void SetId(this object obj, object value) 
=> obj.SetPropValue("Id", value);

Example of create IList and bind to object:

var type = obj.GetType();
var prop = type.GetProperty('Users');
var list = prop.IList();
obj.SetPropValue(prop.Name, list);

Default

Alternative of default for System.Type in runtime based on Expression.Default() with cache available by DefaultExtensions.Default(this Type type):

var type = obj.GetType();
var prop = type.GetProperty('Id');
var value = prop.GetValue(obj);
if(value.Equals(type.Default())
    Console.WriteLine("Property is not initialized!");

Extensions provided not by ExpressionTree

Equivalent of C# 'as'

As<T>(this object)
As<T>(this object, bool throw)
As<T>(this object, T default)

Equivalent of C# 'is/not' check

Is<T>(this object)
Is<T>(this object, out T match)
IsNot<T>(this object)
IsNot<T>(this object, out T match)
Is<T>(this Type)
Is<T>(this Type, out T match)
IsNot<T>(this Type)
IsNot<T>(this Type, out T match)

Additional methods for 'is something'

IsSimple
IsPrimitive
IsNumericType
IsDateType
IsNullable
IsNullablePrimitive
IsAnonymousType
IsICollection
IsDbCollection

Additional methods for IEnumerable

'String' checks differenlty

IsEmpty
IsNotEmpty

Call

Extensions for call methods by ExpressionTrees Available methods for 'call':

obj.Call("Equalls",null);
dbCtx.CallGeneric("Set",new Type[]{ typeof(User) });
typeof(Console).CallStatic("WriteLine", "log");
list.CallExtension("ToList",typeof("EnumerableExtensions");

Overloads for call static generic, call generic extension, Call with T result etc included.

Example of using Call chain with LiteDatabase: gettin anonymous class from store in runtime:

var liteDbCollectionQueryable = LiteDb
    .CallGeneric("GetCollection", new Type[] { type })
    .Call("FindAll")
    .CallGenericExtension("ToList", typeof(Enumerable), new[] { type })
    .CallGenericExtension("AsQueryable", typeof(Queryable), new[] { type });
    
var filtered = SelectionModelConverter
    .CallGeneric("Convert", new Type[] { type }, selection, liteDbCollectionQueryable)
    .GetPropertyExprRaw("Result");
    
var (filteredPropertyConverted, anonymousType) = SelectionModelConverter
    .CallGeneric<(IQueryable, Type)>("ConvertProperties", new Type[] { type }, selection.Properties, filtered); // returns IQueryable and anonymousType
    
var materialize = filteredPropertyConverted.CallGenericExtension("ToList", typeof(Enumerable), new[] { anonymousType });

TypeFromAssemblyExtensions

Extensions for getting Types and instances of Type from Assembly and assembly names loaded from AppDomain.Current.BasePath.

Note about performance (package version 1.0.0)

That's not speed-up alternative. You can check it by run some benchmarks. That's alternative of System.Reflection. With .NET6 all techniques of 'speed-up' by ExpressionTrees and even source generators is pointless because of reflection improvements described here: https://devblogs.microsoft.com/dotnet/performance-improvements-in-net-6/#reflection But still it can be useful alternative for full .NET Framework with 'old' runtime.

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