Basic metaclass magic is working

.gitignore

@@ -0,0 +1 @@
+*.pyc

README.md

@@ -1,4 +1,14 @@
 wicken
 ======
-
 metadata companion library for paegan data model
+
+
+description
+============
+
+Wicken is built on a Object Relational Mapper. It assumes a mapping exists between a flat namespace which will be used as properties in the object classes for ease of access and the schema for a particular data encoding. For instance the schema might be ISO 19115-2 and the data encoding XML, or the schema might be CF and the encoding NetCDF.
+
+Concrete classes implement the _get and _set methods for a particular encoding, while
+the class for a particular mapping is generated at run time from a mapping. Most of the magic happens in a few lines of meta programming...
+
+

example_script.py

@@ -0,0 +1,29 @@
+
+
+from wicken.dogma import NetCDFDogma
+from netCDF4 import Dataset
+
+rootGrp = Dataset('myfile.nc','w') # open a new file for read/write...
+
+
+metadata_beliefs = {
+    'service_provider_name':'publisher_name',
+    'service_provider_contact_info':'publisher_email'}
+# typically loaded from a file - a modified version of the IOOS Asset_SOS_MAP
+
+
+# Make metadata object instance using the NetCDFDogma class to work with a NetCDF data objects metadata using CF conventions
+metadata = NetCDFDogma('CF',metadata_beliefs, rootGrp)
+
+print 'Class name: ', metadata.__class__.__name__
+
+
+print metadata.service_provider_name
+
+metadata.service_provider_name = 'ASA'
+
+print metadata.service_provider_name
+
+# Now use the netcdf method...
+
+print metadata._dataObject.ncattrs()

wicken/dogma.py

@@ -0,0 +1,155 @@
+#!/usr/bin/env python
+'''
+@author David Stuebe <dstuebe@asasscience.com>
+@file dogma.py
+@date 06/03/13
+@description The dogma module provides a metaclass based approach to mapping a flat name 
+space for class properties to any storage format and metadata schema. Example classes are
+implemented for a dictionary storage. A particular mapping from the flat namespace used for
+the properties to the metadata schema must be provided at runtime. 
+'''
+
+from lxml import etree
+from netCDF4 import Dataset
+
+
+class Tenants(object):
+    def __init__(self, belief, teaching, doc=None):
+        '''
+        belief is a string which will become a property of a particular dogma object
+        teaching is the string, collection or object that is used by the _set and 
+        _get method of this Dogma to map a belieft about what a metadata element should be 
+        called by IOOS to a particular schema, say ISO XML or NetCDF CF.
+        '''
+        self.belief = belief
+        self.teaching = teaching
+        if doc: self.__doc__ = doc
+
+    def __get__(self, dogma, objtype=None):
+        print '__get__:', self.belief
+        return dogma._get(self.teaching)
+
+    def __set__(self, dogma, value):
+        print '__set__:',self.belief
+        dogma._set(self.teaching,value)
+
+    def __delete__(self, dogma):
+        raise NotImplementedError('Can not delete the %s property!' % self.belief)
+
+class MetaReligion(type):
+
+    def __call__(cls, religion, beliefs, *args, **kwargs):
+        '''
+        cls is the base class which new properties will be added to
+        religion is the unique prefix for that class and its beliefs (properties)
+        beliefs is a dictionary that maps property names (IOOS metadata) to a particular schema (ISO, CF, etc) 
+        '''
+        print 'call: religion: ', religion
+        print 'call: beliefs: ', beliefs
+        clsName = religion + cls.__name__
+        clsDict={}
+        clsDict['_religion'] = religion
+        clsDict['_beliefs'] = beliefs
+
+
+        for belief, teaching in beliefs.iteritems():
+            clsDict[belief] = Tenants(belief, teaching)
+
+
+        clsType = MetaReligion.__new__(MetaReligion, clsName, (cls,), clsDict)
+
+
+        # Finally allow the instantiation to occur, but slip in our new class type
+        obj = super(MetaReligion, clsType).__call__(religion, beliefs, *args, **kwargs)
+
+        return obj
+
+
+
+class Dogma(object):
+    __metaclass__ = MetaReligion
+
+    def __init__(self, religion, beliefs, dataObject):
+        print 'init: religion: ', religion
+        print 'init: beliefs: ', beliefs
+        print 'init: dataObect', dataObject
+
+        self._dataObject = dataObject
+
+
+
+    def _get(self, key):
+        raise NotImplementedError('_get Method is not implemented in the Dogma Base Class!')
+
+    def _set(self, key, value):
+        raise NotImplementedError('_set Method is not implemented in the Dogma Base Class!')
+
+
+class DictionaryDogma(Dogma):
+
+    def __init__(self, religion, beliefs, dataObject=None):
+
+        if dataObject is None:
+            dataObject = {}
+
+        if not isinstance(dataObject, dict):
+            raise TypeError('DictionaryDogma only allows dictionary data objects!')
+
+        super(DictionaryDogma, self).__init__(religion, beliefs, dataObject)   
+
+    def _get(self,key):        
+        return self._dataObject.get(key)
+
+    def _set(self,key,value):
+        self._dataObject.__setitem__(key,value)
+
+
+class XmlDogma(Dogma):
+
+    def __init__(self, religion, beliefs, dataObject=None):
+
+        if dataObject is None:
+            dataObject = etree.Element('root') # ???
+
+        if not isinstance(dataObject, etree._Element):
+            raise TypeError('XmlDogma only allows XML Element data objects!')
+
+        super(XmlDogma, self).__init__(religion, beliefs, dataObject)   
+
+    def _get(self,xpath_args):        
+        return self._dataObject.xpath(*xpath_args).text # Needs testing
+
+    def _set(self,key,value):
+        element = self._dataObject.xpath(*xpath_args)
+        element.text = value
+
+
+class NetCDFDogma(Dogma):
+
+
+    def __init__(self, religion, beliefs, dataObject=None):
+
+        if dataObject is None: # allow none - what is the title?
+            dataObject = Dataset('junk_metadata.nc','w')
+
+        if not isinstance(dataObject, Dataset):
+            raise TypeError('NetCDFDogma only allows NetCDF4 Dataset data objects!')
+
+        super(NetCDFDogma, self).__init__(religion, beliefs, dataObject)   
+
+    def _get(self,key):        
+        try:
+            return getattr(self._dataObject,key)
+        except AttributeError:
+            return None
+
+    def _set(self,key,value):
+        setattr(self._dataObject,key,value)
+
+    def _write(self):
+
+        self._dataObject.close()
+
+
+
+

wicken/etree.py

@@ -0,0 +1,54 @@
+# =============================================================================
+# OWSLib. Copyright (C) 2005 Sean C. Gillies
+#
+# Contact email: sgillies@frii.com
+# =============================================================================
+
+def patch_well_known_namespaces(etree_module):
+    """Monkey patches the etree module to add some well-known namespaces."""
+    etree_module._namespace_map.update({
+            "http://www.w3.org/1999/02/22-rdf-syntax-ns#":  "rdf", 
+            "http://purl.org/rss/1.0/":                     "rss", 
+            "http://purl.org/rss/1.0/modules/taxonomy/":    "taxo", 
+            "http://purl.org/dc/elements/1.1/":             "dc", 
+            "http://purl.org/rss/1.0/modules/syndication/": "syn", 
+            "http://www.w3.org/2003/01/geo/wgs84_pos#":     "geo",
+            "http://www.opengis.net/cat/csw/2.0.2":         "csw",
+            "http://purl.org/dc/terms/":                    "dct",
+            "http://www.isotc211.org/2005/gco":             "gco",
+            "http://www.isotc211.org/2005/gmd":             "gmd",
+            "http://www.isotc211.org/2005/gts":             "gts",
+            "http://www.isotc211.org/2005/srv":             "srv",
+            "http://www.fgdc.gov":                          "fgdc",
+            "http://gcmd.gsfc.nasa.gov/Aboutus/xml/dif/":   "dif",
+            "http://www.opengis.net/gml":                   "gml",
+            "http://www.opengis.net/ogc":                   "ogc",
+            "http://www.opengis.net/ows":                   "ows",
+            "http://www.opengis.net/ows/1.1":               "ows",
+            "http://www.opengis.net/ows/2.0":               "ows",
+            "http://www.opengis.net/wms":                   "wms",
+            "http://www.opengis.net/context":               "wmc",
+            "http://www.opengis.net/wfs":                   "wfs",
+            "http://www.opengis.net/sos/1.0":               "sos",
+            "urn:oasis:names:tc:ebxml-regrep:xsd:rim:3.0":  "rim",
+            "http://www.w3.org/2001/XMLSchema":             "xs",
+            "http://www.w3.org/XML/Schema":                 "xs2",
+            "http://www.w3.org/2001/XMLSchema-instance":    "xsi",
+            "http://www.w3.org/1999/xlink":                 "xlink"})
+
+# try to find lxml or elementtree
+try:
+    from lxml import etree
+except ImportError:
+    try:
+        # Python 2.5 with ElementTree included
+        import xml.etree.ElementTree as etree
+        patch_well_known_namespaces(etree)
+    except ImportError:
+        try:
+            # Python < 2.5 with ElementTree installed
+            import elementtree.ElementTree as etree
+            patch_well_known_namespaces(etree)
+        except ImportError:
+            raise RuntimeError('You need either lxml or ElementTree to use OWSLib!')
+

wicken/util.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python
+'''
+@author David Stuebe <dstuebe@asasscience.com>
+@file util.py
+@date 06/03/13
+@description Utility module for functions and helpers
+'''
+
+
+
+from pprint import pprint
+import StringIO
+
+
+
+def pretty_print(obj):
+
+    contents = "Pretty Print Failed :-("
+    try:
+        output = StringIO.StringIO()
+        pprint(obj, output)
+        contents = output.getvalue()
+    finally:
+        output.close()
+    return contents