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sonolus.script.record

For usage details, see the corresponding concepts page.

Record

Bases: GenericValue

Base class for user-defined data structures.

Note

A field whose type is itself a reference type, such as another Record or an Array, stores a reference to the value passed to the constructor rather than a copy, so mutating one mutates the other. Assigning to such a field afterward copies the assigned value's data into the field's existing storage in place rather than rebinding the field, so the update is visible through any other reference to that storage. Fields of a value type such as Num are always independent, both at construction and on assignment.

class Box[T](Record):
    value: T

inner = Box(1)
outer = Box(inner)  # outer.value aliases inner; no copy is made
inner.value = 2
assert outer.value.value == 2  # mutating inner is visible through outer

outer.value = Box(3)  # copies the new value into the shared storage in place
assert inner.value == 3  # inner is updated too, since outer.value still aliases it

A field annotated with typing.Final is set when the record is created and cannot be assigned afterward. Finality applies to the binding rather than to the data behind it, so the contents of a Final field of a reference type can still be changed through it.

class Marker(Record):
    time: Final[float]
    hit: bool

marker = Marker(1.0, False)
marker.hit = True  # allowed
marker.time = 2.0  # rejected
Usage

A regular record: 

class MyRecord(Record):
    field1: int
    field2: bool

A generic record: 

class MyGenericRecord[T, U](Record):
    field1: T
    field2: U

Creating an instance: 

record = MyRecord(field1=42, field2=True)
record_2 = MyGenericRecord[int, int](field1=42, field2=100)
record_3 = MyGenericRecord(field1=42, field2=100)  # Type arguments can be inferred
record_4 = +MyRecord  # Create a zero-initialized record
record_5 = +MyGenericRecord[int, int]

Copying a record: 

record_copy = +record

type_var_value(var: TypeVar) -> Any classmethod

Return the value of a type variable.

Parameters:

Name Type Description Default
var TypeVar

The type variable to get the value of.

 required

Returns:

Type Description
Any

The value of the type variable.