BigObject Core::Object

from application core

This is the common base class of all `big' objects in polymake. It does not have any properties, but provides several useful methods for scripting and interactive use.

apply_rule(String pattern)

Executes the specified production rule. If the object does not possess enough initial properties to provide all required rule sources, or any of its preconditions are not satisfied, an exception is raised.

Parameters:

String pattern: either a label (see prefer) or a rule header. The rule header must exactly match the definition in the rulefile, up to white spaces around property names. If the given pattern matches headers of several rules, or the given label is associated with several rules, the rule chain with smallest total weight (including the rules supplying the source properties) is chosen.

attach(String name, Any data, String constructor_args)

Attach an arbitrary data item to a `big' object. Attachments are saved in the same data file as the `big' object itself. They can be retrieved by calling get_attachment.

Parameters:

String name: attachment name, can be an arbitrary string. If an attachment with the given name already exists, it is silently replaced with new data.

Any data: attachment data, can be a simple numeric scalar, a string, or a complex data type, e.g. a Matrix or Polynomial. `Big' objects, anonymous arrays or hashes are not allowed.

String constructor_args: optional list of property names of the owning `big' object which should be passed to the attached data constructor when it will be restored from a data file. Properties of subobjects are specified in dotted path notation. For example, for an attachment of type NodeMap you must specify the “ADJACENCY” property containing the graph the map is referring to.

disable_rules(String pattern)

Temporarily disable production rules matching given pattern for an object. Rules are re-enabled after the complete execution of the current script or input expression in interactive mode. Works much like the user function disable_rules but only affecting the given object.

Parameters:

String pattern: either a label (see prefer) or a rule header. The rule header must exactly match the definition in the rulefile, up to white spaces around property names. If the given pattern matches headers of several rules, or the given label is associated with several rules, they all will be disabled regardless their precoditions, weights, or other attributes.

dont_save

Clears the `changed' flag in the object, so that it won't be saved in the XML file it stems from. This method is primarily designed for unit tests, but could be also useful in interactive mode if you want to revert all recent changes and reload the object from the data file.

get_attachment(String name)

Retrieve data stored in the given attachment.

Parameters:

String name: attachment name

get_schedule(String request)

Compose an optimal chain of production rules providing all requested properties. The returned RuleChain object can be applied to the original object as well as to any other object with the same initial set of properties. If no feasible rule chain exists, `undef' is returned. To watch the rule scheduler at work, e.g. to see announcements about tried preconditions, you may temporarily increase the verbosity levels $Verbose::rules and $Verbose::scheduler.

Parameters:

String request: name of a property with optional alternatives or a property path in dotted notation. Several requests may be listed.

Returns:

Core::RuleChain

Example:

generate an optimal rule chain for a parameterized family of polytopes:

 > @p=map { new Polytope("POINTS" => my_matrix($_) ) } 1..10;
 > $s=$p[0]->get_schedule("FACETS", "TRIANGULATION.FACETS");
 > $s->apply($_) for @p;

list_attachments

Return names of all attachments as a list of strings.

list_names

Returns the list of names of multiple subobject instances. This method can be applied to any instance of a multiple subobject. For a normal (non-multiple) subobject or a top-level object just returns its name.

Example:

List all names of linear programs associated with a polytope:

 > print join(" ", $p->LP->list_names);

list_properties(Bool deep)

Returns the list of names of all properties kept in the object.

Parameters:

Bool deep: recursively descend in all subobjects and list their properties in dotted notation.

properties()

Returns or prints a string with all properties (names and values) and subobjects.

Options:

Int maxdepth: descend into subobjects up to given depth, default 0

remove(String prop)

Remove the property prop from the object. The property must be mutable, multiple, or unambiguously reconstructible from the remaining properties.

Parameters:

String prop: property name or a path to a property in a subobject in dotted notation, Several properties may be removed at once.

remove(Core::Object subobj)

Remove the multiple subobject instance(s) from the object.

Parameters:

Core::Object subobj: multiple subobject instance. Several subobjects may be removed at once.

remove_attachment(String name)

Remove the given attachment from the `big' object.

Parameters:

String name: attachment name

Returns:

Any

set_as_default

Makes the multiple subobject instance the default one. Physically this means moving it at the 0-th position in the instance list. The instance can be selected by give() or PROPERTY_NAME access method.

Example:

by current position:

 > $p->TRIANGULATION->[$i]->set_as_default;

Example:

by subobject name:

 > $p->TRIANGULATION("placing")->set_as_default;

Example:

by checking for a specific property:

 > $p->TRIANGULATION(sub { defined($_->lookup("WEIGHTS")) })->set_as_default;

Example:

by analyzing all instances and picking the best one:

 > for (@{$p->TRIANGULATION}) { assign_min($min_facets, $_->N_FACETS) and $t=$_ } $t->set_as_default;

set_as_default_now

Temporarily make the multiple subobject instance the default one. The change is automatically reverted at the end of the current user cycle. Usage as set_as_default.