The mooR Book

Property Information Functions

property_info

Description: Retrieves information about a property on an object.
Arguments:

• : The object that has the property object
• : The name of the property to get information about prop-name

Returns: A list containing two elements:

1. The owner of the property (object reference)
2. A string representing the permission flags: 'r' (read), 'w' (write), 'c' (clear)

Note: Requires read permission on the property.

set_property_info

Description: Changes the permission information for a property.
Arguments:

• : The object with the property to modify object
• : The name of the property to modify prop-name
• : A list containing permission information: [owner, permissions] or [owner, permissions, new-name]
  • : The new owner of the property (object reference) owner
  • : A string containing the permission flags (combination of 'r', 'w', 'c') permissions
  • new-name: Optional new name for the property

info

Returns: An empty list
Note: Requires appropriate permissions to modify the property.

Property Management Functions

add_property

Description: Adds a new property to an object.
Arguments:

• : The object to add the property to object
• : The name for the new property prop-name
• : The initial value for the property value
• : A list containing permission information (same format as in ) infoset_property_info``

Returns: none
Note: Requires appropriate permissions to add properties to the object.

delete_property

Description: Removes a property from an object.
Arguments:

• : The object to remove the property from object
• : The name of the property to remove prop-name

Returns: An empty list
Note: Requires ownership of the property or the object.

Property Value Functions

is_clear_property

Description: Checks if a property is cleared, meaning its value will be resolved transitively from a parent object through prototype inheritance.
Arguments:

• : The object to check object
• : The name of the property to check prop-name

Returns: A boolean value (true if the property is clear)
Note: Requires read permission on the property.

clear_property

Description: Clears a property, making its value be resolved transitively from a parent object through prototype inheritance.
Arguments:

• : The object with the property to clear object
• : The name of the property to clear prop-name

Returns: An empty list
Note: Requires write permission on the property.

Property Permissions Explained

Properties in this system use a permission model based on the following flags:

• (read): Controls who can read the property's value r
• w (write): Controls who can change the property's value
• (clear): Controls who can clear the property, allowing its value to be resolved from parent objects c

These permissions are represented as a string (e.g., "rwc" for all permissions, "r" for read-only).

Property Info List Format

Several functions use a property info list format:

• Two-element format: [owner, permissions]
• Three-element format: [owner, permissions, new-name]

Where:

• is an object reference owner
• is a string containing the permission flags (combination of 'r', 'w', 'c') permissions
• new-name (when present) is a string representing the new name for the property

Property Inheritance

This system uses prototype-based inheritance for properties:

• When a property is "cleared" on an object, it doesn't store its own value
• Instead, when accessing a cleared property, the system looks for that property on parent/prototype objects
• This enables efficient inheritance of property values without duplication