Thanks for you patience, Dave.
Obviously i have not got used to the python philosophy.
Following you guide, i implemented the following code, and you are
absolutely right.
#!/usr/bin/python
#coding:utf-8
class Parent(object):
def __init__(self):
pass
def displayAttrOfSubClass(self):
print self.attrFromChild
class Child(Parent):
def __init__(self):
self.attrFromChild = 'Hi, Everyone, Java does this support this trick!'
childObj = Child()
childObj.displayAttrOfSubClass()
Python can use in the parent class a variable only instantiated by a
sub-class, is this a point of advance of technique of Python?
Jim
On Wed, May 20, 2009 at 6:00 PM, Dave Angel <da...@ieee.org> wrote:
> Jim Qiu wrote:
>
>> Hi everyone,
>>
>> Following is the code i am reading, i don't see anywhere the declaration
>> of
>> Message.root object,
>> Where is it from?
>>
>> #bots-modules
>> import bots.botslib as botslib
>> import bots.node as node
>> from bots.botsconfig import *
>>
>>
>> class Message(object):
>> ''' abstract class; represents a edi message.
>> is subclassed as outmessage or inmessage object.
>> '''
>> def __init__(self):
>> self.recordnumber=0 #segment counter. Is not used
>> for
>> UNT of SE record; some editypes want sequential recordnumbering
>>
>> @staticmethod
>> def display(records):
>> '''for debugging lexed records.'''
>> for record in records:
>> t = 0
>> for veld in record:
>> if t==0:
>> print '%s (Record-id)'%(veld[VALUE])
>> else:
>> if veld[SFIELD]:
>> print ' %s (sub)'%(veld[VALUE])
>> else:
>> print ' %s (veld)'%(veld[VALUE])
>> t += 1
>>
>> def get(self,*mpaths):
>> ''' query tree (self.root) with mpath; get value (string); get None
>> if not found.'''
>> if self.root.record is None:
>> raise botslib.MpathRootError('get("%s"): "root" of incoming
>> message is empty; either split messages or use inn.getloop'%(str(mpaths)))
>> return self.root.get(*mpaths)
>>
>> def getnozero(self,*mpaths):
>> ''' like get, returns None is value is zero (0) or not numeric.
>> Is sometimes usefull in mapping.'''
>> if self.root.record is None:
>> raise botslib.MpathRootError('get("%s"): "root" of incoming
>> message is empty; either split messages or use inn.getloop'%(str(mpaths)))
>> return self.root.getnozero(*mpaths)
>>
>> def getindicator(self,ind,*mpaths):
>> ''' like get, returns None is value is zero (0) or not numeric.
>> Is sometimes usefull in mapping.'''
>> if self.root.record is None:
>> raise botslib.MpathRootError('get("%s"): "root" of incoming
>> message is empty; either split messages or use inn.getloop'%(str(mpaths)))
>> return self.root.getindicator(ind,*mpaths)
>>
>> def getcount(self):
>> ''' count number of nodes in self.root. Number of nodes is number
>> of
>> records.'''
>> return self.root.getcount()
>>
>> def getcountoccurrences(self,*mpaths):
>> ''' count number of nodes in self.root. Number of nodes is number
>> of
>> records.'''
>> count = 0
>> for value in self.getloop(*mpaths):
>> count += 1
>> return count
>>
>> def getcountsum(self,*mpaths):
>> ''' return the sum for all values found in mpath. Eg total number
>> of
>> ordered quantities.'''
>> if self.root.record is None:
>> raise botslib.MpathRootError('get("%s"): "root" of incoming
>> message is empty; either split messages or use inn.getloop'%(str(mpaths)))
>> return self.root.getcountsum(*mpaths)
>>
>> def getloop(self,*mpaths):
>> ''' query tree with mpath; generates all the nodes. Is typically
>> used as: for record in inn.get(mpath):
>> '''
>> if self.root.record: #self.root is a real root
>> for terug in self.root.getloop(*mpaths): #search recursive for
>> rest of mpaths
>> yield terug
>> else: #self.root is dummy root
>> for childnode in self.root.children:
>> for terug in childnode.getloop(*mpaths): #search recursive
>> for rest of mpaths
>> yield terug
>>
>> def put(self,*mpaths):
>> if self.root.record is None and self.root.children:
>> raise botslib.MpathRootError('put("%s"): "root" of outgoing
>> message is empty; use out.putloop'%(str(mpaths)))
>> return self.root.put(*mpaths)
>>
>> def putloop(self,*mpaths):
>> if not self.root.record: #no input yet, and start with a
>> putloop(): dummy root
>> if len(mpaths) == 1:
>> self.root.append(node.Node(mpaths[0]))
>> return self.root.children[-1]
>> else: #TODO: what if self.root.record is None and len(mpaths) >
>> 1?
>> raise botslib.MpathRootError('putloop("%s"): mpath too
>> long???'%(str(mpaths)))
>> return self.root.putloop(*mpaths)
>>
>> def sort(self,*mpaths):
>> if self.root.record is None:
>> raise botslib.MpathRootError('get("%s"): "root" of message is
>> empty; either split messages or use inn.getloop'%(str(mpaths)))
>> self.root.sort(*mpaths)
>>
>> def normalisetree(self,node):
>> ''' The node tree is check, sorted, fields are formated etc.
>> Always use this method before writing output.
>> '''
>> #~ node.display()
>> #~ print 'normalisetree'
>> self._checktree(node,self.defmessage.structure[0])
>> self._canonicaltree(node,self.defmessage.structure[0])
>>
>> def _checktree(self,tree,structure):
>> ''' checks tree with table:
>> - all records should be in table at the right place in
>> hierarchy
>> - for each record, all fields should be in grammar
>> This function checks the root of grammar-structure with root of
>> node tree
>> '''
>> if tree.record['BOTSID'] == structure[ID]:
>> #check tree recursively with structure
>> self._checktreecore(tree,structure)
>> else:
>> raise botslib.MessageError('(Root)record %s of %s not in table
>> %s'%(tree.record['BOTSID'],tree.record,self.defmessage.grammarname))
>>
>> def _checktreecore(self,node,structure):
>> ''' recursive
>> '''
>> deletelist=[]
>> self._checkfields(node.record,structure)
>> if node.children and not LEVEL in structure:
>> if self.ta_info['checkunknownentities']:
>> raise botslib.MessageError('Record "%s" in message has
>> children, but structure of grammar "%s" not. Found gg
>>
>> "%s".'%(node.record['BOTSID'],self.defmessage.grammarname,node.children[0].record['BOTSID']))
>> node.children=[]
>> return
>> for childnode in node.children: #for every node:
>> for structure_record in structure[LEVEL]: #search in
>> grammar-records
>> if childnode.record['BOTSID'] == structure_record[ID]:
>> #if
>> found right structure_record
>> #check children recursive
>> self._checktreecore(childnode,structure_record)
>> break #check next mpathnode
>> else: #checked all structure_record in grammar, but nothing
>> found
>> if self.ta_info['checkunknownentities']:
>> raise botslib.MessageError('Record "%s" in message not
>> in structure of grammar "%s". Whole record:
>>
>> "%s".'%(childnode.record['BOTSID'],self.defmessage.grammarname,childnode.record))
>> deletelist.append(childnode)
>> for child in deletelist:
>> node.children.remove(child)
>>
>>
>> def _checkfields(self,record,structure_record):
>> ''' checks for every field in record if field exists in
>> structure_record (from grammar).
>> '''
>> deletelist=[]
>> for field in record.keys(): #all fields in record should
>> exist in structure_record
>> for grammarfield in structure_record[FIELDS]:
>> if grammarfield[ISFIELD]: #if field (no composite)
>> if field == grammarfield[ID]:
>> break
>> else: #if composite
>> for grammarsubfield in grammarfield[SUBFIELDS]: #loop
>> subfields
>> if field == grammarsubfield[ID]:
>> break
>> else:
>> continue
>> break
>> else:
>> if self.ta_info['checkunknownentities']:
>> raise botslib.MessageError('Field "%s" does not exist
>> in
>> record: %s'%(field,structure_record[MPATH]))
>> #~ raise botslib.MessageError('Field "%s" does not
>> exist
>> in record: %s'%(field,structure_record[ID])) #alt voor MPATH
>> #~ raise botslib.MessageError('Field "%s" does not
>> exist
>> in record: %s'%(field,structure_record[FIELDS])) #folder, text is too
>> long
>> deletelist.append(field)
>> for field in deletelist:
>> del record[field]
>>
>> def _canonicaltree(self,node,structure,headerrecordnumber=0):
>> ''' For nodes: check min and max occurence; sort the nodes conform
>> grammar
>> For fields: check M/C; format the fields.
>> '''
>> sortednodelist = []
>> self._canonicalfields(node.record,structure,headerrecordnumber)
>> #write the fields
>> if LEVEL in structure:
>> for structure_record in structure[LEVEL]: #for
>> structure_record
>> of this level in grammar
>> count = 0 #count number of
>> occurences of record
>> for childnode in node.children: #for every node
>> in mpathtree; SPEED: delete nodes from list when found
>> if childnode.record['BOTSID'] != structure_record[ID]:
>> #if it is not the right NODE":
>> continue
>> count += 1
>>
>> self._canonicaltree(childnode,structure_record,self.recordnumber)
>> #use rest of index in deeper level
>> sortednodelist.append(childnode)
>> if structure_record[MIN] > count:
>> raise botslib.MessageError('Record "%s": mandatory but
>> not present.'%(structure_record[MPATH]))
>> if structure_record[MAX] < count:
>> raise botslib.MessageError('Record "%s": occures to
>> often (%s times).'%(structure_record[MPATH],count))
>> node.children=sortednodelist
>> if hasattr(self,'do_queries'):
>> self.do_queries(node,structure)
>>
>> def
>> _canonicalfields(self,noderecord,structure_record,headerrecordnumber):
>> ''' For fields: check M/C; format the fields. Field are not sorted
>> here (a dict can not be sorted)
>> '''
>> #~ print noderecord
>> for grammarfield in structure_record[FIELDS]:
>> if grammarfield[ISFIELD]: #if field (no composite)
>> value = noderecord.get(grammarfield[ID],'')
>> #~ print 'check field',grammarfield,value
>> if not value:
>> if grammarfield[MANDATORY] == 'M':
>> raise botslib.MessageError('Record "%s": mandatory
>> field "%s" not filled.'%(structure_record[MPATH],grammarfield[ID]))
>> elif not grammarfield[MINLENGTH]: #if minlength=0
>> continue
>> noderecord[grammarfield[ID]] =
>> self._formatfield(value,grammarfield,structure_record)
>> else: #if composite
>> compositefilled = False
>> for grammarsubfield in grammarfield[SUBFIELDS]: #loop
>> subfields to see if one of them is there
>> if noderecord.get(grammarsubfield[ID],''):
>> compositefilled = True
>> if not compositefilled:
>> if grammarfield[MANDATORY]=='M':
>> raise botslib.MessageError('Record "%s": mandatory
>> composite "%s" not filled.'%(structure_record[MPATH],grammarfield[ID]))
>> continue
>> for grammarsubfield in grammarfield[SUBFIELDS]: #loop
>> subfields
>> value = noderecord.get(grammarsubfield[ID],'')
>> #~ print 'check subfield',grammarsubfield,value
>> if not value:
>> if grammarsubfield[MANDATORY]=='M':
>> #~ print 'Record "%s": mandatory subfield "%s"
>> not filled:
>> "%s".'%(structure_record[MPATH],grammarsubfield[ID],noderecord)
>> raise botslib.MessageError('Record "%s":
>> mandatory subfield "%s" not filled:
>> "%s".'%(structure_record[MPATH],grammarsubfield[ID],noderecord))
>> else:
>> continue
>> noderecord[grammarsubfield[ID]] =
>> self._formatfield(value,grammarsubfield,structure_record)
>> #~ print 'fill',grammarfield[ID]
>>
>> Thanks in advance.
>>
>> Jim
>>
>>
>>
> Unlike your previous question, this attribute is not referenced in
> __init__(). That, plus the comment about being an abstract class, leads me
> to guess that the derived classes are required to define this attribute.
> That's one of the characteristics of an abstract class; some of the
> details are missing, and intended to be supplied by a child class.
>
> What do the docs for this abstract class say? If they don't discuss how to
> implement a concrete class, they're sadly lacking.
>
>
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