Return returns nothing in recursive function

[Matthew Warren]

Hallo people,

I have the following code that implements a simple recursive tree like
structure.

The trouble is with the GetTreeBranch function, the print statement
prints a valid value but the return immediatley afterward doesn't return
anything.

Can anyone help me with why?


Thanks,

Matt.

Code and output follow;

'''
dirtree

A simple implementation of a filesystem-like tree
datastructure.
'''

def MakeNewTree(rootname='root'):
    '''MakeNewTree

    Creates an empty tree with a 'root' node.
    If the parameter rootname is not given, it
    defaults to 'root'.
    '''
    return [{rootname:[]}]

def DoThingsToTree(path,value,tree,delete=False):
    '''_DoThingsToTree

    You should not use this function.
    '''
    if type(path)==type(''):
        path=path.lstrip('/').rstrip('/').split('/')
    for item in tree:
        if type(item)==type({}) and item.has_key(path[0]):
            if len(path)==1:
                if not delete:
                    try:
                        item[path[0]].append(value)
                    except KeyError:
                        item[path[0]]=value
                else:
                    if value is not None:
                        del(item[path[0]][value])
                    else:
                        del(tree[tree.index(item)])
                break
            else:
                _DoThingsToTree(path[1:],value,item[path[0]],delete)

def GetTreeBranch(path,tree):
    if type(path)==type(''):
        path=path.lstrip('/').rstrip('/').split('/')
    for item in tree:
        if type(item)==type({}) and item.has_key(path[0]):
            if len(path)==1:
                print 'returning',tree[tree.index(item)]
                return tree[tree.index(item)]
            else:
                GetTreeBranch(path[1:],item[path[0]])        

def AddItemToTree(path,value,tree):
    '''AddITemToTree

    Add an item onto a 'branch' of the tree.
    path    should be a '/' separated string that
            defines a path to the branch required.
    value   an object to put onto the branch
    tree    the tree to operate on.
    '''
    DoThingsToTree(path,value,tree)
    
def AddBranchToTree(path,branch,tree):
    '''AddBranchToTree

    Add a new branch to the tree.
    path    should be a '/' separated string that
            defines a path to the branch required.
    branch  an object used as the branch identifier
            (usually a string)
    tree    the tree to operate on
    '''
    DoThingsToTree(path,{branch:[]},tree)
                    
def DelItemFromTree(path,index,tree):
    '''DelItemFromTree

    Remove an item from the tree.
    path    should be a '/' separated string that
            defines a path to the branch required.
    index   the numeric index of the item to delete
            on the branch to delete. items are indexed
            in the order they are added, from 0
    '''
    DoThingsToTree(path,index,tree,delete=True)
    

def DelBranchFromTree(path,tree):
    '''DelBranchFromTree

    Remove a branch and all items and subbranches.
    path    should be a '/' separated string that
            defines a path to the branch required.
    tree    The tree to delete the branch from.
    '''
    DoThingsToTree(path,None,tree,delete=True)


OUTPUT;

>>> from dirtree import *
>>> MyTree=MakeNewTree('Matt')
>>> AddBranchToTree('Matt','Good',MyTree)
>>> AddBranchToTree('Matt','Bad',MyTree)
>>> AddItemToTree('Matt/Good','Computers',MyTree)
>>> AddItemToTree('Matt/Bad','Drinking',MyTree)
>>> a=GetTreeBranch('Matt/Bad',MyTree)
returning {'Bad': ['Drinking']}
>>> a
>>>


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