clipspy 0.0.9

CLIPS Python bindings

Python CFFI bindings for CLIPS 6.30

Installation

The CLIPS shared library and headers must be installed within the system.

If library and headers are not in the system default locations, they can be specified to the installer via the CFLAGS and LDFLAGS environment variables.

# CFLAGS="-I<headers path>" LDFLAGS="-L<library path>" pip install pyclips

Design principles

The clipspy bindings aim to be a “pythonic” thin layer built on top of the CLIPS native C APIs. Most of the functions and the methods directly resolve to the CLIPS functions documented in the Advanced Programming Guide.

Python standard paradigms are preferred such as property getters and setters, generators and magic methods.

Data types

The mapping between CLIPS and Python types is as follows.

CLIPS	Python
INTEGER	int
FLOAT	float
STRING	str
SYMBOL	Symbol *
MULTIFIELD	list
FACT_ADDRESS	Fact **
INSTANCE_ADDRESS	Instance
EXTERNAL_ADDRESS	ffi.CData

* The Python Symbol object is a interned string

** ImpliedFact and TemplateFact are Fact subclasses

Namespaces

To keep the Environment interface simple, the CLIPS functions have been grouped into five different namespaces. Each namespace is accessible via an Environment specific attribute.

• Environment.facts: facts and templates

• Environment.agenda: rules and activations

• Environment.classes: classes and instances

• Environment.modules: modules and global variables

• Environment.functions: functions, generics and methods

Objects lifecycle

All clipspy objects are simple wrappers of CLIPS data structures. This means every object lifecycle is bound to the CLIPS data structure it refers to.

In most of the cases, deleting or undefining an object makes it unusable.

Example:

template = env.facts.find_template('some-fact')

# remove the Template from the CLIPS Environment
template.undefine()  # from here on, the template object is unusable

# this will cause an error
print(template)

If the previous example is pretty straightforward, there are more subtle scenarios.

templates = tuple(env.facts.templates())

# remove all CLIPS constructs from the environment
env.clear()  # from here on, all the previously created objects are unusable

# this will cause an error
for template in templates:
    print(template)

API Documentation

The doc folder contains the sources to generate the documentation via sphinx.

Example

from clips import Environment, Symbol

environment = Environment()

# load constructs into the environment
environment.load('constructs.clp')

# assert a fact as string
environment.facts.assert_string('(a-fact)')

# retrieve a fact template
template = environment.facts.find_template('a-fact')

# create a new fact from the template
fact = template.new_fact()

# implied (ordered) facts are accessed as lists
fact.append(42)
fact.extend(("foo", "bar"))

# assert the fact within the environment
fact.assertit()

# retrieve another fact template
template = environment.facts.find_template('another-fact')
fact = template.new_fact()

# template (unordered) facts are accessed as dictionaries
fact["slot-name"] = Symbol("foo")

fact.assertit()

# execute the activations in the agenda
environment.agenda.run()