API reference - Class Manager

Notation used in Ruby API documentation

Module: db

Description: A transaction manager class

Manager objects control layout and potentially other objects in the layout database and queue operations to form transactions. A transaction is a sequence of operations that can be undone or redone.

In order to equip a layout object with undo/redo support, instantiate the layout object with a manager attached and embrace the operations to undo/redo with transaction/commit calls.

The use of transactions is subject to certain constraints, i.e. transacted sequences may not be mixed with non-transacted ones.

This class has been introduced in version 0.19.

Public constructors

new Manager ptrnewCreates a new object of this class

Public methods

void_createEnsures the C++ object is created
void_destroyExplicitly destroys the object
[const]bool_destroyed?Returns a value indicating whether the object was already destroyed
[const]bool_is_const_object?Returns a value indicating whether the reference is a const reference
void_manageMarks the object as managed by the script side.
void_unmanageMarks the object as no longer owned by the script side.
voidcommitClose a transaction.
[const]boolhas_redo?Determine if a transaction is available for 'redo'
[const]boolhas_undo?Determine if a transaction is available for 'undo'
voidredoRedo the next available transaction
unsigned longtransaction(string description)Begin a transaction
unsigned longtransaction(string description,
unsigned long join_with)
Begin a joined transaction
[const]stringtransaction_for_redoReturn the description of the next transaction for 'redo'
[const]stringtransaction_for_undoReturn the description of the next transaction for 'undo'
voidundoUndo the current transaction

Deprecated methods (protected, public, static, non-static and constructors)

voidcreateUse of this method is deprecated. Use _create instead
voiddestroyUse of this method is deprecated. Use _destroy instead
[const]booldestroyed?Use of this method is deprecated. Use _destroyed? instead
[const]boolis_const_object?Use of this method is deprecated. Use _is_const_object? instead

Detailed description

_create

Signature: void _create

Description: Ensures the C++ object is created

Use this method to ensure the C++ object is created, for example to ensure that resources are allocated. Usually C++ objects are created on demand and not necessarily when the script object is created.

_destroy

Signature: void _destroy

Description: Explicitly destroys the object

Explicitly destroys the object on C++ side if it was owned by the script interpreter. Subsequent access to this object will throw an exception. If the object is not owned by the script, this method will do nothing.

_destroyed?

Signature: [const] bool _destroyed?

Description: Returns a value indicating whether the object was already destroyed

This method returns true, if the object was destroyed, either explicitly or by the C++ side. The latter may happen, if the object is owned by a C++ object which got destroyed itself.

_is_const_object?

Signature: [const] bool _is_const_object?

Description: Returns a value indicating whether the reference is a const reference

This method returns true, if self is a const reference. In that case, only const methods may be called on self.

_manage

Signature: void _manage

Description: Marks the object as managed by the script side.

After calling this method on an object, the script side will be responsible for the management of the object. This method may be called if an object is returned from a C++ function and the object is known not to be owned by any C++ instance. If necessary, the script side may delete the object if the script's reference is no longer required.

Usually it's not required to call this method. It has been introduced in version 0.24.

_unmanage

Signature: void _unmanage

Description: Marks the object as no longer owned by the script side.

Calling this method will make this object no longer owned by the script's memory management. Instead, the object must be managed in some other way. Usually this method may be called if it is known that some C++ object holds and manages this object. Technically speaking, this method will turn the script's reference into a weak reference. After the script engine decides to delete the reference, the object itself will still exist. If the object is not managed otherwise, memory leaks will occur.

Usually it's not required to call this method. It has been introduced in version 0.24.

commit

Signature: void commit

Description: Close a transaction.

create

Signature: void create

Description: Ensures the C++ object is created

Use of this method is deprecated. Use _create instead

Use this method to ensure the C++ object is created, for example to ensure that resources are allocated. Usually C++ objects are created on demand and not necessarily when the script object is created.

destroy

Signature: void destroy

Description: Explicitly destroys the object

Use of this method is deprecated. Use _destroy instead

Explicitly destroys the object on C++ side if it was owned by the script interpreter. Subsequent access to this object will throw an exception. If the object is not owned by the script, this method will do nothing.

destroyed?

Signature: [const] bool destroyed?

Description: Returns a value indicating whether the object was already destroyed

Use of this method is deprecated. Use _destroyed? instead

This method returns true, if the object was destroyed, either explicitly or by the C++ side. The latter may happen, if the object is owned by a C++ object which got destroyed itself.

has_redo?

Signature: [const] bool has_redo?

Description: Determine if a transaction is available for 'redo'

Returns:True, if a transaction is available.

has_undo?

Signature: [const] bool has_undo?

Description: Determine if a transaction is available for 'undo'

Returns:True, if a transaction is available.

is_const_object?

Signature: [const] bool is_const_object?

Description: Returns a value indicating whether the reference is a const reference

Use of this method is deprecated. Use _is_const_object? instead

This method returns true, if self is a const reference. In that case, only const methods may be called on self.

new

Signature: [static] new Manager ptr new

Description: Creates a new object of this class

Python specific notes:
This method is the default initializer of the object

redo

Signature: void redo

Description: Redo the next available transaction

The next transaction is redone with this method. The 'has_redo' method can be used to determine whether there are transactions to undo.

transaction

(1) Signature: unsigned long transaction (string description)

Description: Begin a transaction

description:The description for this transaction.
Returns:The ID of the transaction (can be used to join other transactions with this one)

This call will open a new transaction. A transaction consists of a set of operations issued with the 'queue' method. A transaction is closed with the 'commit' method.

(2) Signature: unsigned long transaction (string description, unsigned long join_with)

Description: Begin a joined transaction

description:The description for this transaction (ignored if joined).
description:The ID of the previous transaction.
Returns:The ID of the new transaction (can be used to join more)

This call will open a new transaction and join if with the previous transaction. The ID of the previous transaction must be equal to the ID given with 'join_with'.

This overload was introduced in version 0.22.

transaction_for_redo

Signature: [const] string transaction_for_redo

Description: Return the description of the next transaction for 'redo'

transaction_for_undo

Signature: [const] string transaction_for_undo

Description: Return the description of the next transaction for 'undo'

undo

Signature: void undo

Description: Undo the current transaction

The current transaction is undone with this method. The 'has_undo' method can be used to determine whether there are transactions to undo.