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Python native serialization is the Python-only wire mode selected with xlang=False. Use it when every writer and reader is Python and the payload should follow Python's object model instead of the portable xlang type system.

Use Xlang Serialization, the default Python mode, when bytes must be read by Java, C++, Go, Rust, JavaScript/TypeScript, C#, Swift, Dart, Scala, Kotlin, or another non-Python Fory runtime.

When To Use Native Serialization

Use native serialization when:

  • A payload is produced and consumed only by Python applications.
  • You are replacing pickle or cloudpickle for Python-only object graphs.
  • The data model includes functions, lambdas, local classes, methods, or Python reduction hooks.
  • The graph can contain shared objects or cycles that need Python reference tracking.
  • You need pickle protocol 5-style out-of-band buffers for large Python data objects.

Native mode can serialize Python-specific values such as global functions, local functions, lambdas, local classes, methods, and objects customized with __getstate__, __setstate__, __reduce__, or __reduce_ex__. Those values are not valid xlang payloads.

Create a Native Runtime

Create Fory with xlang=False:

import pyfory
fory = pyfory.Fory(xlang=False, ref=False, strict=True)

Keep strict=True for registered, trusted type surfaces. Use strict=False only when native-mode payloads need dynamic Python types such as functions, local classes, or objects reconstructed by reduction hooks.

Common Usage

import pyfory

fory = pyfory.Fory(xlang=False, ref=True, strict=False)

data = fory.dumps({"name": "Alice", "age": 30, "scores": [95, 87, 92]})
print(fory.loads(data))

from dataclasses import dataclass

@dataclass
class Person:
    name: str
    age: int

person = Person("Bob", 25)
data = fory.dumps(person)
print(fory.loads(data))  # Person(name='Bob', age=25)

Use dumps/loads for pickle-style APIs, or serialize/deserialize when matching the xlang API shape in code that switches modes explicitly.

Security And Dynamic Types

Native mode can reconstruct Python objects that execute import and construction logic during deserialization. Treat untrusted native-mode bytes the same way you would treat untrusted pickle bytes.

  • Keep strict=True when deserializing data that should contain only registered or built-in types.
  • Use strict=False only for trusted payloads that require dynamic Python classes or functions.
  • Provide a policy= deserialization policy when dynamic types are required but the accepted type surface should still be restricted.
  • Do not use xlang/native mode choice as a security control. Apply strict mode, policies, registration, and resource limits based on the payload source.

References And Cycles

Enable ref=True when object identity, shared references, or cycles must round-trip:

import pyfory

fory = pyfory.Fory(xlang=False, ref=True, strict=True)

node = {}
node["self"] = node
data = fory.dumps(node)
decoded = fory.loads(data)
assert decoded["self"] is decoded

Disable reference tracking for value-shaped payloads that do not need identity preservation. It keeps the payload smaller and the hot path simpler.

Pickle And Cloudpickle Replacement

Native mode is the Python mode to choose when the existing boundary uses pickle or cloudpickle. It supports richer Python values than JSON and xlang mode, including Python functions, local classes, closures, and reduction hooks.

Use xlang mode instead when the payload crosses language boundaries or the data model should be a portable schema shared with other Fory runtimes.

Serialize Global Functions

Capture and serialize functions defined at module level. Fory deserializes and returns the same function object:

import pyfory

fory = pyfory.Fory(xlang=False, ref=True, strict=False)

def my_global_function(x):
    return 10 * x

data = fory.dumps(my_global_function)
print(fory.loads(data)(10))  # 100

Serialize Local Functions/Lambdas

Serialize functions with closures and lambda expressions. Fory captures the closure variables automatically:

import pyfory

fory = pyfory.Fory(xlang=False, ref=True, strict=False)

# Local functions with closures
def my_function():
    local_var = 10
    def local_func(x):
        return x * local_var
    return local_func

data = fory.dumps(my_function())
print(fory.loads(data)(10))  # 100

# Lambdas
data = fory.dumps(lambda x: 10 * x)
print(fory.loads(data)(10))  # 100

Serialize Global Classes/Methods

Serialize class objects, instance methods, class methods, and static methods:

from dataclasses import dataclass
import pyfory
fory = pyfory.Fory(xlang=False, ref=True, strict=False)

@dataclass
class Person:
    name: str
    age: int

    def f(self, x):
        return self.age * x

    @classmethod
    def g(cls, x):
        return 10 * x

    @staticmethod
    def h(x):
        return 10 * x

# Serialize global class
print(fory.loads(fory.dumps(Person))("Bob", 25))  # Person(name='Bob', age=25)

# Serialize instance method
print(fory.loads(fory.dumps(Person("Bob", 20).f))(10))  # 200

# Serialize class method
print(fory.loads(fory.dumps(Person.g))(10))  # 100

# Serialize static method
print(fory.loads(fory.dumps(Person.h))(10))  # 100

Serialize Local Classes/Methods

Serialize classes defined inside functions along with their methods:

from dataclasses import dataclass
import pyfory
fory = pyfory.Fory(xlang=False, ref=True, strict=False)

def create_local_class():
    class LocalClass:
        def f(self, x):
            return 10 * x

        @classmethod
        def g(cls, x):
            return 10 * x

        @staticmethod
        def h(x):
            return 10 * x
    return LocalClass

# Serialize local class
data = fory.dumps(create_local_class())
print(fory.loads(data)().f(10))  # 100

# Serialize local class instance method
data = fory.dumps(create_local_class()().f)
print(fory.loads(data)(10))  # 100

# Serialize local class method
data = fory.dumps(create_local_class().g)
print(fory.loads(data)(10))  # 100

# Serialize local class static method
data = fory.dumps(create_local_class().h)
print(fory.loads(data)(10))  # 100

Custom Python Object Hooks

Native mode respects common Python customization hooks:

import pyfory

class SessionToken:
    def __init__(self, value):
        self.value = value

    def __getstate__(self):
        return {"value": self.value}

    def __setstate__(self, state):
        self.value = state["value"]

fory = pyfory.Fory(xlang=False, strict=False)
token = fory.loads(fory.dumps(SessionToken("abc")))
print(token.value)  # abc

Use these hooks for Python-only payloads. For xlang payloads, model the data as dataclasses with portable field annotations instead.

Out-of-Band Buffers

Python native mode can use pickle protocol 5-style out-of-band buffers for large binary payloads and data structures backed by external memory:

import pickle
import pyfory

data = b"Large binary data"
pickle_buffer = pickle.PickleBuffer(data)

buffer_objects = []
fory = pyfory.Fory(xlang=False, ref=True, strict=False)
serialized = fory.dumps(pickle_buffer, buffer_callback=buffer_objects.append)
buffers = [obj.getbuffer() for obj in buffer_objects]
decoded = fory.loads(serialized, buffers=buffers)
assert bytes(decoded.raw()) == data

Use this when the payload stays in Python and large buffers should avoid extra copies. See Out-of-Band Serialization.

Native And Xlang Comparison

RequirementUse native serializationUse xlang serialization
Python-only payloadsYesOptional
Non-Python readers or writersNoYes
Functions, lambdas, local classesYesNo
__reduce__ / __getstate__ object hooksYesNo
Pickle/cloudpickle replacementYesNo
Portable type mapping across runtimesNoYes

Performance Comparison

import pyfory
import pickle
import timeit

fory = pyfory.Fory(xlang=False, ref=True, strict=False)

obj = {f"key{i}": f"value{i}" for i in range(10000)}
print(f"Fory: {timeit.timeit(lambda: fory.dumps(obj), number=1000):.3f}s")
print(f"Pickle: {timeit.timeit(lambda: pickle.dumps(obj), number=1000):.3f}s")

Troubleshooting

Another language cannot read the payload

The writer is using native serialization. Rebuild it with xlang=True, register portable schemas on every peer runtime, and avoid Python-only values such as lambdas or local classes.

A dynamic class or function fails to deserialize

Use strict=False for trusted payloads and provide a deserialization policy= when only selected dynamic types should be accepted.

A cycle does not round-trip

Create the runtime with ref=True.

A value depends on pickle hooks

Keep the payload in native mode. Xlang mode does not execute Python __reduce__, __reduce_ex__, __getstate__, or __setstate__ object reconstruction hooks.

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