Namespace Libplanet.Action

Classes

ActionEvaluation

A record type to represent an evaluation plan and result of a single action.

ActionTypeAttribute

Indicates that an action class (i.e., a class implementing IAction) can be held by transactions and blocks. It also gives an action class a TypeIdentifier for serialization and deserialization.

MissingActionTypeException

The exception that is thrown when an action class without ActionTypeAttribute is tried to used with PolymorphicAction<T>.

PolymorphicAction<T>

A decorator to enable subtype polymorphism for action classes.

By convention, concrete action subclasses are named with verb phrases, e.g., Heal, Sell.

One downside of this compared to the vanilla IAction is the fact that it uses reflection under the hood. This may cause compatibility issues on certain platforms, and is slightly slower.

RandomExtension

This extension class provides some convenient methods to deal with IRandom.

UnexpectedlyTerminatedActionException

The exception that is thrown during an IAction is being evaluated.

The actual exception that the Action threw is stored in the property.

Interfaces

IAccountStateDelta

An interface to manipulate account states with maintaining the set of UpdatedAddresses.

It is like a map which is virtually initialized such that every possible Address exists and is mapped to null. That means that:

it does not have length,
its index getter never throws , but returns null instead, and
filling an Address with null state cannot be distinguished from the Address having never been set to any state.

IAction

An in-game action. Every action should be replayable, because multiple nodes in a network should execute an action and get the same result.

A “class” which implements this interface is analogous to a function, and its instance is analogous to a partial function application, in other words, a function with some bound arguments. Those parameters that will be bound at runtime should be represented as fields or properties in an action class, and bound argument values to these parameters should be received through a constructor parameters of that class.

From a perspective of security, an action class belongs to the network protocol, and property values in an action belong to a node's will (i.e., a user/player's choice). That means if you define an action class it also defines what every honest node can do in the network. Even if a malicious node changes their own action code it won't affect other honest nodes in the network.

For example, where honest nodes share the common action Heal(Target) => PreviousStates[Target] + 1, suppose a malicious node m changes their own Heal action code to Heal(Target) => PreviousStates[Target] + 2 (2 instead of 1), and then send an action Heal(m). Fortunately, this action does not work as m's intention, because the changed code in itself is not used by other honest nodes, so they still increase only 1, not 2. The effect of that double healing is a sort of “illusion” only visible to the malicious node alone.

In conclusion, action code is a part of the protocol and it works with consensus in the network, so only things each node can affect the network in general is property values of each action they sign and send, not code of an action.

IActionContext

Contextual data determined by a transaction and a block. Passed to Execute(IActionContext) method.

IRandom

An pseudorandom number generator interface equivalent to .

Although these two types have similar shapes, they are not compatible (i.e., disallowed to be casted to each other).

Delegates

AccountStateGetter

An delegate to provide read-only view of account states.

Gets an account state of the given address.

If the given address has never been set its account status, returns null instead of throwing any exception.