namespacecraft 0.3.2

Composable URI namespaces

Namespacecraft

Namespacecraft is a tiny toolkit for composing URI namespaces.

Use

>>> from namespacecraft import Namespace
>>> EX = Namespace('http://example.org/')
>>> EX.a
Term('http://example.org/a')
>>> Namespace('http://example.org').terminates_with('#') / 'a' / 'b' / 'c' + 'x'
Term('http://example.org/a/b/c#x')

Paths

Build paths using the / operator.

>>> Namespace('http://example.org/') / 'a' / 'b' / 'c'
Namespace('http://example.org/a/b/c')

You can pass a list or tuple to / to append multiple path components at once.

>>> Namespace('http://example.org') / [1, 2, 3]
Namespace('http://example.org/1/2/3')

Use terminates_with() to set the final delimiter.

>>> Namespace('http://example.org').terminates_with('#') / 'a' / 'b'
Namespace('http://example.org/a/b#')

Terms

Create terms by accessing a Namespace attribute.

>>> EX = Namespace('http://example.org/')
>>> EX.a
Term('http://example.org/a')

Or by getting an attribute by name.

>>> EX['b']
Term('http://example.org/b')

Or with the + operator.

>>> EX + 1
Term('http://example.org/1')

Namespace will create terms in any class that initialises from str. For example create terms as instances of rdflib.URIRef.

from namespacecraft import Namespace
from rdflib import Graph, URIRef


EX = Namespace('http://example.org/', term_cls=URIRef).terminates_with('/') / 'a/b/c'
graph = Graph()
graph.add((EX.s, EX.p, EX.o))
print(graph.serialize(format='turtle'))

@prefix ns1: <http://example.org/a/b/c/> .

ns1:s ns1:p ns1:o .

Install

pip install namespacecraft

Gotchas

• The + operator returns a Term object. Any further + operations are just string concatenations.

  >>> Namespace('http://example.org/') + 'a'
  Term('http://example.org/a')
  >>> Namespace('http://example.org/') + 'a' + 'b'
  Term('http://example.org/ab')
  

• Namespaces ending with # are always terminal. Any path added via / immediately returns a Term, and further / operations are not allowed.

  >>> BASE = Namespace('http://example.org#')
  >>> BASE / 'section'
  Term('http://example.org#section')
  >>> (BASE / 'section') / 'subsection'
  TypeError: unsupported operand type(s) for /: 'Term' and 'str'
  

• You cannot set a trailing delimiter on a hash namespace. Attempting to do so will raise a ValueError.

  >>> BASE = Namespace('http://example.org#')
  >>> BASE.terminates_with('/')
  ValueError: Cannot set a trailing delimiter on a hash namespace
  

Test

pytest