The Variable class

A backend-agnostic variable in synalinks.

A Variable acts as a container for state. It holds a JSON object value with the corresponding schema and can be updated by the optimizers.

A Variable is different from a JsonDataModel as it can be modified by the optimizers.

Note that the DataModel used for the variable declaration must have a default value for each of its field.

Examples:

Initializing a Variable with a dict:

from typing import List
import synalinks

class Instructions(synalinks.DataModel):
    instructions: List[str] = []

initial_data = {
    "instructions": [
        "For any problem involving division, always round the quotient to "
        "the nearest even number, regardless of the remainder."
    ],
}
variable_from_dict = synalinks.Variable(
    initializer=initial_data,
    data_model=Instructions,
)

Using a synalinks initializer to create a Variable:

from typing import List
import synalinks

class Instructions(synalinks.DataModel):
    instructions: List[str] = []

from synalinks.initializers import Empty

variable_from_initializer = synalinks.Variable(
    initializer=Empty(data_model=Instructions)
)

Updating the value of a Variable:

new_json = {
    "instructions": [
        "When performing division, always check if the division results "
        "in a whole number. If not, express the result as a fraction or "
        "a decimal, depending on the context of the problem."
    ],
}
variable_from_dict.assign(new_json)

Marking a Variable as non-trainable:

from typing import List
import synalinks

class Instructions(synalinks.DataModel):
    instructions: List[str] = []

from synalinks.initializers import Empty

non_trainable_variable = synalinks.Variable(
    initializer=Empty(data_model=Instructions), trainable=False
)

Parameters:

Name	Type	Description	Default
initializer	str | dict | Initializer	Initial value (dict) or callable (Initializer) for initialization. If a callable is used, it should take the arguments data_model.	None
data_model	DataModel	The backend-dependent data model used as spec.	None
trainable	bool	Optional. Boolean indicating if variable is trainable. Defaults to True.	True
name	str	Optional. A unique name for the variable. Automatically generated if not set.	None
description	str	Optional. the description of the variable. Automatically generated if not set by fetching the data model description.	None

Source code in synalinks/src/backend/common/variables.py

class Variable:
    """A backend-agnostic variable in synalinks.

    A `Variable` acts as a container for state.
    It holds a JSON object value with the corresponding schema and can
    be updated by the optimizers.

    A Variable is different from a JsonDataModel as it can be modified by the optimizers.

    Note that the DataModel used for the variable declaration
    **must have a default value** for each of its field.

    Examples:

    **Initializing a `Variable` with a dict:**

    ```python
    from typing import List
    import synalinks

    class Instructions(synalinks.DataModel):
        instructions: List[str] = []

    initial_data = {
        "instructions": [
            "For any problem involving division, always round the quotient to "
            "the nearest even number, regardless of the remainder."
        ],
    }
    variable_from_dict = synalinks.Variable(
        initializer=initial_data,
        data_model=Instructions,
    )
    ```

    **Using a synalinks initializer to create a `Variable`:**

    ```python
    from typing import List
    import synalinks

    class Instructions(synalinks.DataModel):
        instructions: List[str] = []

    from synalinks.initializers import Empty

    variable_from_initializer = synalinks.Variable(
        initializer=Empty(data_model=Instructions)
    )
    ```

    **Updating the value of a `Variable`:**

    ```python
    new_json = {
        "instructions": [
            "When performing division, always check if the division results "
            "in a whole number. If not, express the result as a fraction or "
            "a decimal, depending on the context of the problem."
        ],
    }
    variable_from_dict.assign(new_json)
    ```

    **Marking a `Variable` as non-trainable:**

    ```python
    from typing import List
    import synalinks

    class Instructions(synalinks.DataModel):
        instructions: List[str] = []

    from synalinks.initializers import Empty

    non_trainable_variable = synalinks.Variable(
        initializer=Empty(data_model=Instructions), trainable=False
    )
    ```

    Args:
        initializer (str | dict | Initializer): Initial value (dict) or callable
            (Initializer) for initialization. If a callable is used, it should
            take the arguments `data_model`.
        data_model (DataModel): The backend-dependent data model used as spec.
        trainable (bool): Optional. Boolean indicating if variable is trainable.
            Defaults to `True`.
        name (str): Optional. A unique name for the variable. Automatically generated
            if not set.
        description (str): Optional. the description of the variable. Automatically generated
            if not set by fetching the data model description.
    """

    def __init__(
        self,
        initializer=None,
        data_model=None,
        trainable=True,
        name=None,
        description=None,
    ):
        name = name or auto_name(self.__class__.__name__)
        if not isinstance(name, str) or "/" in name:
            raise ValueError(
                "Argument `name` must be a string and "
                "cannot contain character `/`. "
                f"Received: name={name}"
            )
        self._name = name
        parent_path = current_path()
        if parent_path:
            self._path = current_path() + "/" + name
        else:
            self._path = name

        self._initializer = None
        self._data_model = data_model
        self._trainable = bool(trainable)
        self._json = None

        if in_stateless_scope():
            if callable(initializer):
                self._initializer = initializer
                self._schema = standardize_schema(data_model.get_schema())
                register_uninitialized_variable(self)
            else:
                raise ValueError(
                    "You are attempting to create a variable "
                    "while in a stateless scope. This is disallowed. "
                    "Make sure that all variables are created "
                    "before you start using your module/program objects.\n\n"
                    "In some cases, you might be seeing this error "
                    "because you need to "
                    "implement a `def build(self, input_schema)` method "
                    "on your module/program, which will "
                    "create its variables.\n\n"
                    "In some other cases, you might be seeing this error "
                    "because you are instantiating a `Variable` and "
                    "assigning it to a module without going through "
                    "self.add_variable(). Always prefer "
                    "using these methods "
                    "(with a `data_model` and `initializer` argument)."
                )
        else:
            if callable(initializer):
                self._initialize_with_initializer(initializer)
            else:
                if data_model is None:
                    raise ValueError(
                        "When creating a Variable from an a dict,"
                        "the `data_model` argument should be specified. "
                        f"Received: initializer={initializer} "
                        f"and data_model={data_model}"
                    )
                value = initializer
                self._initialize(value)
                self._schema = standardize_schema(data_model.get_schema())

        if not description:
            if "description" in self._schema:
                self._description = self._schema["description"]
            else:
                self._description = ""
        else:
            self._description = description

    def _deferred_initialize(self):
        """Deferred initialization of the variable.

        Raises:
            ValueError: If the variable is already initialized or
                if attempting to initialize while in a stateless scope.
        """
        if self._json is not None:
            raise ValueError(f"Variable '{self._path}' is already initialized.")

        if in_stateless_scope():
            raise ValueError(
                "You are attempting to initialize a variable "
                "while in a stateless scope. This is disallowed. "
                "Make sure that all variables are initialized "
                "before you start using your module/program objects."
            )
        self._initialize_with_initializer(self._initializer)
        self._initializer = None

    def get_json(self):
        """The current value of the variable.

        Returns:
            (dict): The current value of the variable.
        """
        if in_stateless_scope():
            scope = get_stateless_scope()
            value = scope.get_current_value(self)
            if value is not None:
                return value
        if self._json is None:
            # Uninitialized variable. Return a placeholder.
            # This is fine because it's only ever used
            # in during schema inference / graph tracing
            # (anything else would be a bug, to be fixed.)
            return self._initializer(data_model=self._data_model)
        return self._json

    def prettify_schema(self):
        """Get a pretty version of the JSON schema for display.

        Returns:
            (dict): The indented JSON schema.
        """
        import json

        return json.dumps(self.get_schema(), indent=2)

    def prettify_json(self):
        """Get a pretty version of the JSON object for display.

        Returns:
            (dict): The indented JSON object.
        """
        import json

        return json.dumps(self.get_json(), indent=2)

    def assign(self, value):
        """Assigns a new value to the variable.

        Args:
            value (dict | DataModel | JsonDataModel): The new value to be assigned.
                The value can be an instanciated data model or JSON dict.

        Returns:
            (dict): The assigned value.

        Raises:
            ValueError: If the schema of the target variable and
                the value are incompatible.
        """
        if backend.is_data_model(value):
            value = value.get_json()
        if in_stateless_scope():
            scope = get_stateless_scope()
            scope.add_update((self, value))
        else:
            self._direct_assign(value)
        return value

    def _direct_assign(self, json):
        """Directly assigns a new value to the variable.

        Args:
            json (dict): The new json value to be assigned.
        """
        self._json = json

    def get_schema(self):
        """The schema of the variable.

        Returns:
            (dict): The JSON schema of the variable.
        """
        return self._schema

    def __contains__(self, other):
        """Check if the schema of `other` is contained within the schema of this variable.

        Args:
            other (SymbolicDataModel | DataModel): The data model to compare against this variable's schema.

        Returns:
            (bool): True if `other`'s schema is a subset of this variable's schema.
        """
        from synalinks.src.backend.common.json_schema_utils import contains_schema

        return contains_schema(self.get_schema(), other.get_schema())

    @property
    def trainable(self):
        """Whether the variable is trainable."""
        return self._trainable

    @trainable.setter
    def trainable(self, value):
        self._trainable = bool(value)

    @property
    def name(self):
        """The name of the variable."""
        return self._name

    @property
    def description(self):
        """The description of the variable."""
        return self._description

    @property
    def path(self):
        """The path of the variable within the program or module."""
        return self._path

    def __repr__(self):
        json = None
        if self._json is not None:
            json = self._json
        json_str = f", json={json}" if json is not None else ""
        return f"<Variable path={self.path}, schema={self._schema}{json_str}>"

    def _initialize_with_initializer(self, initializer):
        """Initializes the variable using an initializer object.

        Args:
            initializer (Initializer): The initializer to be used.
        """
        value = initializer()
        self._schema = standardize_schema(initializer.get_schema())
        self._initialize(value)

    def _initialize(self, json):
        """Initializes the variable with a given json dict.

        Args:
            json (dict): The initial value (JSON object dict).
        """
        self._json = json

    def to_json_data_model(self, name=None):
        """Convert the variable into a `JsonDataModel`.

        Returns:
            (JsonDataModel): The equivalent backend-independent data model
        """
        if not name:
            name = self.name
        return JsonDataModel(
            schema=self.get_schema(),
            json=self.get_json(),
            name=name,
        )

    def to_symbolic_data_model(self, name=None):
        """Convert the variable into a `SymbolicDataModel`.

        Returns:
            (SymbolicDataModel): The equivalent symbolic data model
        """
        if not name:
            name = self.name
        return SymbolicDataModel(
            schema=self.get_schema(),
            name=name,
        )

    def get(self, key, default=None):
        """Get wrapper to make it easier to access JSON fields.

        Args:
            key (str): The key to access.
            default (any): The default value if key not found.
        """
        return self.get_json().get(key, default)

    def __getitem__(self, key):
        """Get item wrapper to make it easier to access JSON fields.

        Args:
            key (str): The key to access.
        """
        return self.get_json()[key]

    def keys(self):
        """Keys wrapper to make it easier to access JSON fields."""
        return self.get_json().keys()

    def values(self):
        """Values wrapper to make it easier to access JSON fields."""
        return self.get_json().values()

    def items(self):
        """Items wrapper to make it easier to access JSON fields."""
        return self.get_json().items()

    def update(self, kv_dict):
        """Update wrapper to make easier to modify fields.

        Args:
            kv_dict (dict): The key/value dict to update.
        """
        self._json.update(kv_dict)

description property

The description of the variable.

name property

The name of the variable.

path property

The path of the variable within the program or module.

trainable property writable

Whether the variable is trainable.

__contains__(other)

Check if the schema of other is contained within the schema of this variable.

Parameters:

Name	Type	Description	Default
other	SymbolicDataModel | DataModel	The data model to compare against this variable's schema.	required

Returns:

Type	Description
bool	True if other's schema is a subset of this variable's schema.

Source code in synalinks/src/backend/common/variables.py

def __contains__(self, other):
    """Check if the schema of `other` is contained within the schema of this variable.

    Args:
        other (SymbolicDataModel | DataModel): The data model to compare against this variable's schema.

    Returns:
        (bool): True if `other`'s schema is a subset of this variable's schema.
    """
    from synalinks.src.backend.common.json_schema_utils import contains_schema

    return contains_schema(self.get_schema(), other.get_schema())

__getitem__(key)

Get item wrapper to make it easier to access JSON fields.

Parameters:

Name	Type	Description	Default
key	str	The key to access.	required

Source code in synalinks/src/backend/common/variables.py

def __getitem__(self, key):
    """Get item wrapper to make it easier to access JSON fields.

    Args:
        key (str): The key to access.
    """
    return self.get_json()[key]

assign(value)

Assigns a new value to the variable.

Parameters:

Name	Type	Description	Default
value	dict | DataModel | JsonDataModel	The new value to be assigned. The value can be an instanciated data model or JSON dict.	required

Returns:

Type	Description
dict	The assigned value.

Raises:

Type	Description
ValueError	If the schema of the target variable and the value are incompatible.

Source code in synalinks/src/backend/common/variables.py

def assign(self, value):
    """Assigns a new value to the variable.

    Args:
        value (dict | DataModel | JsonDataModel): The new value to be assigned.
            The value can be an instanciated data model or JSON dict.

    Returns:
        (dict): The assigned value.

    Raises:
        ValueError: If the schema of the target variable and
            the value are incompatible.
    """
    if backend.is_data_model(value):
        value = value.get_json()
    if in_stateless_scope():
        scope = get_stateless_scope()
        scope.add_update((self, value))
    else:
        self._direct_assign(value)
    return value

get(key, default=None)

Get wrapper to make it easier to access JSON fields.

Parameters:

Name	Type	Description	Default
key	str	The key to access.	required
default	any	The default value if key not found.	None

Source code in synalinks/src/backend/common/variables.py

def get(self, key, default=None):
    """Get wrapper to make it easier to access JSON fields.

    Args:
        key (str): The key to access.
        default (any): The default value if key not found.
    """
    return self.get_json().get(key, default)

get_json()

The current value of the variable.

Returns:

Type	Description
dict	The current value of the variable.

Source code in synalinks/src/backend/common/variables.py

def get_json(self):
    """The current value of the variable.

    Returns:
        (dict): The current value of the variable.
    """
    if in_stateless_scope():
        scope = get_stateless_scope()
        value = scope.get_current_value(self)
        if value is not None:
            return value
    if self._json is None:
        # Uninitialized variable. Return a placeholder.
        # This is fine because it's only ever used
        # in during schema inference / graph tracing
        # (anything else would be a bug, to be fixed.)
        return self._initializer(data_model=self._data_model)
    return self._json

get_schema()

The schema of the variable.

Returns:

Type	Description
dict	The JSON schema of the variable.

Source code in synalinks/src/backend/common/variables.py

def get_schema(self):
    """The schema of the variable.

    Returns:
        (dict): The JSON schema of the variable.
    """
    return self._schema

items()

Items wrapper to make it easier to access JSON fields.

Source code in synalinks/src/backend/common/variables.py

def items(self):
    """Items wrapper to make it easier to access JSON fields."""
    return self.get_json().items()

keys()

Keys wrapper to make it easier to access JSON fields.

Source code in synalinks/src/backend/common/variables.py

def keys(self):
    """Keys wrapper to make it easier to access JSON fields."""
    return self.get_json().keys()

prettify_json()

Get a pretty version of the JSON object for display.

Returns:

Type	Description
dict	The indented JSON object.

Source code in synalinks/src/backend/common/variables.py

def prettify_json(self):
    """Get a pretty version of the JSON object for display.

    Returns:
        (dict): The indented JSON object.
    """
    import json

    return json.dumps(self.get_json(), indent=2)

prettify_schema()

Get a pretty version of the JSON schema for display.

Returns:

Type	Description
dict	The indented JSON schema.

Source code in synalinks/src/backend/common/variables.py

def prettify_schema(self):
    """Get a pretty version of the JSON schema for display.

    Returns:
        (dict): The indented JSON schema.
    """
    import json

    return json.dumps(self.get_schema(), indent=2)

to_json_data_model(name=None)

Convert the variable into a JsonDataModel.

Returns:

Type	Description
JsonDataModel	The equivalent backend-independent data model

Source code in synalinks/src/backend/common/variables.py

def to_json_data_model(self, name=None):
    """Convert the variable into a `JsonDataModel`.

    Returns:
        (JsonDataModel): The equivalent backend-independent data model
    """
    if not name:
        name = self.name
    return JsonDataModel(
        schema=self.get_schema(),
        json=self.get_json(),
        name=name,
    )

to_symbolic_data_model(name=None)

Convert the variable into a SymbolicDataModel.

Returns:

Type	Description
SymbolicDataModel	The equivalent symbolic data model

Source code in synalinks/src/backend/common/variables.py

def to_symbolic_data_model(self, name=None):
    """Convert the variable into a `SymbolicDataModel`.

    Returns:
        (SymbolicDataModel): The equivalent symbolic data model
    """
    if not name:
        name = self.name
    return SymbolicDataModel(
        schema=self.get_schema(),
        name=name,
    )

update(kv_dict)

Update wrapper to make easier to modify fields.

Parameters:

Name	Type	Description	Default
kv_dict	dict	The key/value dict to update.	required

Source code in synalinks/src/backend/common/variables.py

def update(self, kv_dict):
    """Update wrapper to make easier to modify fields.

    Args:
        kv_dict (dict): The key/value dict to update.
    """
    self._json.update(kv_dict)

values()

Values wrapper to make it easier to access JSON fields.

Source code in synalinks/src/backend/common/variables.py

def values(self):
    """Values wrapper to make it easier to access JSON fields."""
    return self.get_json().values()