create_protocol/3 — The Logtalk Handbook v3.47.0 documentation

# `create_protocol/3`

## Description

    create_protocol(Identifier, Relations, Directives)

Creates a new, dynamic, protocol. This predicate is often used as a primitive to implement high-level protocol creation methods.

Note that, when opting for runtime generated protocol identifiers, it’s possible to run out of identifiers when using a backend Prolog compiler with bounded integer support. The portable solution, when creating a large number of dynamic protocols in long-running applications, is to recycle, whenever possible, the identifiers.

When using Logtalk multi-threading features, predicates calling this built-in predicate may need to be declared synchronized in order to avoid race conditions.

## Modes and number of proofs

    create_protocol(?protocol_identifier, @list(protocol_relation), @list(protocol_directive)) - one

## Errors

Either `Relations` or `Directives` is a variable:
`instantiation_error`
`Identifier` is neither a variable nor a valid protocol identifier:
`type_error(protocol_identifier, Identifier)`
`Identifier` is already in use:
`permission_error(modify, category, Identifier)`
`permission_error(modify, object, Identifier)`
`permission_error(modify, protocol, Identifier)`
`Relations` is neither a variable nor a proper list:
`type_error(list, Relations)`
Repeated entity relation clause:
`permission_error(repeat, entity_relation, extends/1)`
`Directives` is neither a variable nor a proper list:
`type_error(list, Directives)`

## Examples

    | ?- create_protocol(
            logging,
            [extends(monitoring)],
            [public([log_file/1, log_on/0, log_off/0])]
         ).

See also

abolish_protocol/1, current_protocol/1, protocol_property/2, conforms_to_protocol/2-3, extends_protocol/2-3, implements_protocol/2-3