Logtalk is a mature Open Source object-oriented logic programming language that can use most Prolog implementations as a back-end compiler.

As a multi-paradigm language, Logtalk includes support for both prototypes and classes, protocols (interfaces), component-based programming through category-based composition, event-driven programming, and high-level multi-threading programming.

NOTE: After installation, each Logtalk user should run the shell command logtalk_user_setup, which creates a logtalk directory on the user's home directory containing library files, examples, and documentation.

Here are some key features of "Logtalk":

· Predicate directives (declarations) may be contained inside protocols (interfaces), which may be implemented by any object.
· Object names can be compound terms containing free variables that can be used to parametrize object predicates. This allows us to treat any predicate as an instantiation of a parametric object. I.e. through parametric object we can associate any number of methods with a compound term.
· You may have, in the same application, class-based hierarchies (with instantiation and specialization relations) and prototype-based hierarchies (with extension relations). Moreover, fundamental language features such as protocols (interfaces) and categories (components) can be used simultaneously by classes, instances, and prototypes.
· No need to be constrained to a single, lengthy hierarchy rooted in some generic object.
· Logtalk supports private, protected, and public inheritance in a way similar to C . Moreover, any entity relation can be qualified using a scope keyword. E.g. an object can privately implement a protocol, thus making all protocol declared predicates private.
· Set the scope of your object predicates to match your protocol design and let the runtime system enforce your choices.
· Objects can be either static or dynamic. Static objects are defined in source files which are compiled and loaded in the same way as Prolog files. Dynamic object can be either defined in source files or created at runtime.
· Any static object may contain both static and dynamic predicates.
· Logtalk uses standard Prolog syntax with the addition of a few operators and directives for a smooth learning curve. Prolog code can be easily encapsulated inside objects with little or no changes. Moreover, Logtalk can transparently interpret most Prolog modules as Logtalk objects for easy reusing of existing code (e.g. libraries).
· Predicates can be implicitly called when a spied event occurs, allowing programming solutions which minimize object coupling. In addition, events provide support for behavioral reflection.
· Predicates can be encapsulated inside categories, which can be virtually imported by any object, without any code duplication and irrespective of object hierarchies. Thus, objects may be defined through composition of categories, which act as fine-grained units of code reuse.
· High level multi-threading programming is available when running Logtalk with selected back-end Prolog compilers, allowing objects to support both synchronous and asynchronous messages. Easily take advantage of modern multi-processor and multi-core computers without bothering with the details of creating and destroying threads, implement thread communication, or synchronizing threads.
· Logtalk supports multi-inheritance of both protocol and implementation. An object may implement several protocols and extend, specialize, or instantiate several objects. Multi-inheritance conflicts are solved implicitly by the Logtalk lookup algorithms or explicitly by using predicate directives.
· Logtalk code is compiled using the same technics that you use to write efficient Prolog code. In addition, Logtalk supports both static binding and dynamic binding (with method lookup caching), greatly improving performance. Benchmark results for some Prolog compilers are available here.
· Logtalk is designed for smooth integration with any Prolog compiler that conforms or closely follows the ISO Prolog Standard.
· Logtalk interfaces with a specific back-end Prolog compiler via a minimal configuration file making it compatible with almost any modern compiler.
· Logtalk automatically generates a documentation file in XML format for every compiled object, protocol, or category. The system includes all the necessary XSL(T) files and scripts to convert documenting files to (X)HTML and PDF.

Requirements:

· Prolog

What's New in This Release: [ read full changelog ]

· Changed the compiler to take into account the uses/2 directive when compiling calls to the reflection built-in methods. This change extends the semantics of the uses/2 directive and allows easier migration from plain Prolog applications to Logtalk.
· Updated the implementation of the predicate_property/2 built-in method, adding a scope/1 property.
· Updated the Logtalk compiler to add information about a source file name, source file directory, and source file compiler options to the generated Prolog files. In previous versions, this information was registered only when loading a source file. The changes simplify building applications where Logtalk libraries are pre-compiled and pre-loaded.
· Updated the Logtalk compiler to print the name of the hook object used in the compilation of source files when the "hook" compiler flag is defined.
· Updated the built-in debugger in order to avoid unnecessary choice points created by back-end Prolog compilers whose retract/1 implementation fails to tak...