Class ExpressionFieldDescriptor<T, TValue>

Definition

Namespace: StardewUI.Framework.Descriptors
Assembly: StardewUI.dll

Implementation of a field descriptor using a compiled expression tree.

public class ExpressionFieldDescriptor<T, TValue> : 
    StardewUI.Framework.Descriptors.IPropertyDescriptor<TValue>, 
    StardewUI.Framework.Descriptors.IPropertyDescriptor, 
    StardewUI.Framework.Descriptors.IMemberDescriptor

Type Parameters

T
The field's declaring type.

TValue
The field's value type.

Inheritance
Object ⇦ ExpressionFieldDescriptor<T, TValue>

Implements
IPropertyDescriptor<TValue>, IPropertyDescriptor, IMemberDescriptor

Remarks

Expression trees take a long time to compile and should only be compiled in the background, but once compiled are nearly equivalent to a regular field access.

Members

Properties

Name	Description
CanRead	Whether or not the property is readable, i.e. has a public getter.
CanWrite	Whether or not the property is writable, i.e. has a public setter.
DeclaringType	The type on which the member is declared.
IsAutoProperty	Whether or not the property is likely auto-implemented.
IsField	Whether or not the underlying member is a field, rather than a real property.
Name	The member name.
ValueType	The property's value type.

Methods

Name	Description
Build(FieldInfo)	Builds a new ExpressionFieldDescriptor<T, TValue> instance from the specified field.
GetValue(Object)	Reads the current property value.
SetValue(Object, TValue)	Writes a new property value.

Details

Properties

CanRead

Whether or not the property is readable, i.e. has a public getter.

public bool CanRead { get; }

Property Value

Boolean

Remarks

For fields, always returns true.

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CanWrite

Whether or not the property is writable, i.e. has a public setter.

public bool CanWrite { get; }

Property Value

Boolean

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DeclaringType

The type on which the member is declared.

public System.Type DeclaringType { get; }

Property Value

Type

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IsAutoProperty

Whether or not the property is likely auto-implemented.

public bool IsAutoProperty { get; }

Property Value

Boolean

Remarks

Auto-property detection is heuristic, relying on the method's IL instructions and the name of its backing field. This can often be interpreted as a signal that the property won't receive property-change notifications, since to do so (whether explicitly or via some weaver/source generator) requires an implementation that is different from the auto-generated getter and setter.

Caveats: This only works as a negative signal (a value of false does not prove that the property will receive notifications, even if the declaring type implements INotifyPropertyChanged), and is somewhat fuzzy even as a negative signal; it is theoretically possible for a source generator or IL weaver to leave behind all the markers of an auto property and still emit notifications, although no known libraries actually do so.

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IsField

Whether or not the underlying member is a field, rather than a real property.

public bool IsField { get; }

Property Value

Boolean

Remarks

For binding convenience, fields and properties are both called "properties" for descriptors, as the external access pattern is the same; however, mutable fields can never reliably emit property-change notifications regardless of whether the declaring type implements INotifyPropertyChanged, so this is usually used to emit some warning.

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Name

The member name.

public string Name { get; }

Property Value

string

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ValueType

The property's value type.

public System.Type ValueType { get; }

Property Value

Type

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Methods

Build(FieldInfo)

Builds a new ExpressionFieldDescriptor<T, TValue> instance from the specified field.

public static StardewUI.Framework.Descriptors.ExpressionFieldDescriptor<T, TValue> Build(System.Reflection.FieldInfo field);

Parameters

field   FieldInfo
The reflected field.

Returns

ExpressionFieldDescriptor<T, TValue>

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GetValue(Object)

Reads the current property value.

public TValue GetValue(System.Object source);

Parameters

source   Object
An instance of the property's DeclaringType.

Returns

TValue

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SetValue(Object, TValue)

Writes a new property value.

public void SetValue(System.Object target, TValue value);

Parameters

target   Object
An instance of the property's DeclaringType.

value   TValue
The new property value.

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