Options

bevy.options.Option

Bases: Generic[_T], ABC

Option types help make code cleaner and typing more consistent. The Value option wraps values while the Null options stand in for no value. Option types are convenient to use with match/case statements.

Example

match result:
    case Value(value):
        ...
    case Null():
        ...

value abstractmethod property

value: _T

Returns the value assigned to the option. This raises Exception if accessed on a Null option.

value_or abstractmethod

value_or(default: _T) -> _T

Returns the value if it is set, otherwise returns the provided default value.

bevy.options.Value

Value(value: _T)

Bases: Option[_T]

The Value option type is used to wrap a value. No matter what the value a Value option always evaluates as True to help identify if an Option has a value set. The Value option can surface its value as a match arg in a match/case statement.

Example

match example:
    case Value(value):
        print(value)

value property

value: _T

Gets the value assigned to the Value option.

value_or

value_or(default: _T) -> _T

Value option always have a value set, this always returns that value.

bevy.options.Null

Null(message: str = '')

Bases: Option

The Null option type represents the absence of a value. The Null option will always evaluate as False to help identify if an Option has a value or not. Null options can take an optional message that will be used in error messages and that can be surfaced as a match arg in match/case statements.

Example

match example:
    case Null(message):
        print(message)

message property

message: str

The exception message the Null option will use if the value is accessed.

value property

value

The Null options never have values so this raises an Exception containing the Null option's message.

value_or

value_or(default: _T) -> _T

Null options never have a value so this only returns default.