NamespaceManager.bind(prefix, namespace, replace=True) leaves existing prefix in place #543
Description
I want to change an existing and bound namespace prefix. From the documentation of NamespaceManager I understand that "bind" with parameter "replace=True" should achieve this. However, while this does associate the namespace with the new prefix, the old prefix remains bound to the same namespace.
This can make it impossible to obtain a serialization with the new prefix. Is this intended behaviour?
Code example:
from rdflib import Graph, Namespace
g = Graph()
g.parse(data="""<?xml version="1.0" encoding="UTF-8"?>
<rdf:RDF
xmlns:ns1="http://somewhere/else#"
xmlns:ns2="http://nowhere/else#"
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>
<rdf:Description rdf:about="http://somewhere/else#y">
<ns2:Q rdf:resource="http://somewhere/else#z"/>
</rdf:Description>
<rdf:Description rdf:about="http://somewhere/else#root">
<ns1:P rdf:resource="http://somewhere/else#y"/>
<ns1:P rdf:resource="http://somewhere/else#x"/>
</rdf:Description>
</rdf:RDF>
""")
for ns in g.namespaces():
print('%s (%s)' % (ns))
# prints:
#
# xml (http://www.w3.org/XML/1998/namespace)
# ns2 (http://nowhere/else#)
# ns1 (http://somewhere/else#)
# rdfs (http://www.w3.org/2000/01/rdf-schema#)
# xsd (http://www.w3.org/2001/XMLSchema#)
# rdf (http://www.w3.org/1999/02/22-rdf-syntax-ns#)
#
# (as expected)
print(g.serialize().decode())
# prints:
#
# <?xml version="1.0" encoding="UTF-8"?>
# <rdf:RDF
# xmlns:ns1="http://somewhere/else#"
# xmlns:ns2="http://nowhere/else#"
# xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
# >
# <rdf:Description rdf:about="http://somewhere/else#y">
# <ns2:Q rdf:resource="http://somewhere/else#z"/>
# </rdf:Description>
# <rdf:Description rdf:about="http://somewhere/else#root">
# <ns1:P rdf:resource="http://somewhere/else#y"/>
# <ns1:P rdf:resource="http://somewhere/else#x"/>
# </rdf:Description>
# </rdf:RDF>
#
# (as expected)
elseNS = Namespace('http://somewhere/else#') # same namespace as ns1 above
g.namespace_manager.bind('there', elseNS, replace=True) # attempt to rebind to other prefix
for ns in g.namespaces():
print('%s (%s)' % (ns))
# prints:
#
# xsd (http://www.w3.org/2001/XMLSchema#)
# there (http://somewhere/else#)
# rdfs (http://www.w3.org/2000/01/rdf-schema#)
# rdf (http://www.w3.org/1999/02/22-rdf-syntax-ns#)
# xml (http://www.w3.org/XML/1998/namespace)
# ns2 (http://nowhere/else#)
# ns1 (http://somewhere/else#)
#
# ("there" and "ns1" are bound to the same namespace)
print(g.serialize().decode())
# prints:
#
# <?xml version="1.0" encoding="UTF-8"?>
# <rdf:RDF
# xmlns:ns1="http://somewhere/else#"
# xmlns:ns2="http://nowhere/else#"
# xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
# >
# <rdf:Description rdf:about="http://somewhere/else#root">
# <ns1:P rdf:resource="http://somewhere/else#x"/>
# <ns1:P rdf:resource="http://somewhere/else#y"/>
# </rdf:Description>
# <rdf:Description rdf:about="http://somewhere/else#y">
# <ns2:Q rdf:resource="http://somewhere/else#z"/>
# </rdf:Description>
# </rdf:RDF>
#
# (in the serialization "ns1" is used, not "there" as was intended)