Struct MixedChange<T1, T2, T3, T4>

Namespace

DynaSharp.Streams

Assembly

DynaSharp.dll

One change of a typed read of several entities: a Change<T> of one of the types, from shop.ReadChangesAsync<Customer, Order>(streams, ...). Ask with change.Is(out Change<Customer>? customer), or handle every case with Match, which is what stays correct when a type is added.

public readonly struct MixedChange<T1, T2, T3, T4> where T1 : IDynamoDbDiscriminated<T1> where T2 : IDynamoDbDiscriminated<T2> where T3 : IDynamoDbDiscriminated<T3> where T4 : IDynamoDbDiscriminated<T4>

Type Parameters

T1

The first type.

T2

The second type.

T3

The third type.

T4

The fourth type.

Inherited Members

ValueType.Equals(object)

ValueType.GetHashCode()

ValueType.ToString()

object.GetType()

object.Equals(object, object)

object.ReferenceEquals(object, object)

Remarks

It is to Change<T> what Mixed<T1, T2, T3, T4> of a mixed read is to an entity, with the same members. That one is a document, which a read fills and From<T>(T) writes; this one holds a change, which is neither. The default value holds nothing, and Match throws on it; a typed read never gives one. A test builds one with the constructor of its type.

Constructors

MixedChange(Change<T1>)

Initializes a new instance of the MixedChange<T1, T2, T3, T4> struct that holds a change of the first type, as a typed read gives it, so that a test of code that handles the changes of a reading builds its input: new MixedChange<Customer, Order, Invoice, Payment>(new Change<Customer> { Kind = OperationType.Insert, After = customer, Record = new ChangeRecord() }).

public MixedChange(Change<T1> change)

Parameters

change Change<T1>

The change.

Remarks

There is one constructor per type, and the type of the argument picks it. Two equal types make the call ambiguous, which does not compile, and a reading of them could not tell them apart either: it throws ArgumentException.

Exceptions

ArgumentNullException

change is null.

MixedChange(Change<T2>)

Initializes a new instance of the MixedChange<T1, T2, T3, T4> struct that holds a change of the second type, as a typed read gives it, so that a test of code that handles the changes of a reading builds its input: new MixedChange<Customer, Order, Invoice, Payment>(new Change<Order> { Kind = OperationType.Insert, After = order, Record = new ChangeRecord() }).

public MixedChange(Change<T2> change)

Parameters

change Change<T2>

The change.

Remarks

There is one constructor per type, and the type of the argument picks it. Two equal types make the call ambiguous, which does not compile, and a reading of them could not tell them apart either: it throws ArgumentException.

Exceptions

ArgumentNullException

change is null.

MixedChange(Change<T3>)

Initializes a new instance of the MixedChange<T1, T2, T3, T4> struct that holds a change of the third type, as a typed read gives it, so that a test of code that handles the changes of a reading builds its input: new MixedChange<Customer, Order, Invoice, Payment>(new Change<Invoice> { Kind = OperationType.Insert, After = invoice, Record = new ChangeRecord() }).

public MixedChange(Change<T3> change)

Parameters

change Change<T3>

The change.

Remarks

There is one constructor per type, and the type of the argument picks it. Two equal types make the call ambiguous, which does not compile, and a reading of them could not tell them apart either: it throws ArgumentException.

Exceptions

ArgumentNullException

change is null.

MixedChange(Change<T4>)

Initializes a new instance of the MixedChange<T1, T2, T3, T4> struct that holds a change of the fourth type, as a typed read gives it, so that a test of code that handles the changes of a reading builds its input: new MixedChange<Customer, Order, Invoice, Payment>(new Change<Payment> { Kind = OperationType.Insert, After = payment, Record = new ChangeRecord() }).

public MixedChange(Change<T4> change)

Parameters

change Change<T4>

The change.

Remarks

There is one constructor per type, and the type of the argument picks it. Two equal types make the call ambiguous, which does not compile, and a reading of them could not tell them apart either: it throws ArgumentException.

Exceptions

ArgumentNullException

change is null.

Methods

Is(out Change<T1>?)

Gets the change if it is of the first type.

public bool Is(out Change<T1>? change)

Parameters

change Change<T1>

The change, or null.

Returns

bool

true if the change is of this type.

Is(out Change<T2>?)

Gets the change if it is of the second type.

public bool Is(out Change<T2>? change)

Parameters

change Change<T2>

The change, or null.

Returns

bool

true if the change is of this type.

Is(out Change<T3>?)

Gets the change if it is of the third type.

public bool Is(out Change<T3>? change)

Parameters

change Change<T3>

The change, or null.

Returns

bool

true if the change is of this type.

Is(out Change<T4>?)

Gets the change if it is of the fourth type.

public bool Is(out Change<T4>? change)

Parameters

change Change<T4>

The change, or null.

Returns

bool

true if the change is of this type.

Match(Action<Change<T1>>, Action<Change<T2>>, Action<Change<T3>>, Action<Change<T4>>)

Does something with the change, with one action per type, so no type can be forgotten.

public void Match(Action<Change<T1>> first, Action<Change<T2>> second, Action<Change<T3>> third, Action<Change<T4>> fourth)

Parameters

first Action<Change<T1>>

What to do with a change of the first type.

second Action<Change<T2>>

What to do with a change of the second type.

third Action<Change<T3>>

What to do with a change of the third type.

fourth Action<Change<T4>>

What to do with a change of the fourth type.

Exceptions

ArgumentNullException

An action is null.

InvalidOperationException

This is the default value, which holds nothing.

Match<TResult>(Func<Change<T1>, TResult>, Func<Change<T2>, TResult>, Func<Change<T3>, TResult>, Func<Change<T4>, TResult>)

Computes a result from the change, with one function per type, so no type can be forgotten.

public TResult Match<TResult>(Func<Change<T1>, TResult> first, Func<Change<T2>, TResult> second, Func<Change<T3>, TResult> third, Func<Change<T4>, TResult> fourth)

Parameters

first Func<Change<T1>, TResult>

What to do with a change of the first type.

second Func<Change<T2>, TResult>

What to do with a change of the second type.

third Func<Change<T3>, TResult>

What to do with a change of the third type.

fourth Func<Change<T4>, TResult>

What to do with a change of the fourth type.

Returns

TResult

The result of the function of the type of the change.

Type Parameters

TResult

The type of the result.

Exceptions

ArgumentNullException

A function is null.

InvalidOperationException

This is the default value, which holds nothing.