ΘΕΜΑ: Τόσα χρόνια στην Python και δεν το γνώριζα αυτό!

import struct
 
class BNode:
 
    children          = []
    word              = []
    index             = []
    parent            = -1
    page              = -1
    totalAmountOfKeys = 0
    maxChildren       = 0
    uselessBytes      = 0
    bufferSize        = 0
 
 
    #-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-Constructor-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-#
    def __init__(self, bufferSize):
        '''Initialize the node.'''
 
        #Lets say, k = keys and k+1 = Order of Btree.
        #How many keys can i have? (page+parent = 8).
 
        # k*16 + (k+1)*4 + 8 <= bufferSize
        # k*16 + 4*k + 4 + 8 <= bufferSize
        # 20*k + 12 <= bufferSize
        # k <= (bufferSize - 12) / 20
 
        self.totalAmountOfKeys = k = (bufferSize - 12) // 20
        self.maxChildren       = c = self.totalAmountOfKeys + 1
        self.uselessBytes      = bufferSize - (k*16 + c*4 + 8)
        self.bufferSize        = bufferSize
 
 
        #Initialize the children array.
        for i in range(self.maxChildren):
            self.children.append(-1)
            pass
 
        #Initialize the key pairs.
        for i in range(self.totalAmountOfKeys):
            self.word.append("123456789ASD")
            self.index.append(-1)
            pass
 
        return
    #-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-Constructor-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-#
 
 
 
 
    #==================================Write==================================#
    def write(self, file, page):
 
        #Seek into the file.
        file.seek(self.bufferSize * page)
 
        #Create the buffer.
        buffer = bytes()
 
        #----------Add to the buffer all the pairs of (word, index)----------#
        for i in range( len(self.word) ):
            buffer += str.encode(self.word[i]) + struct.pack("i", self.index[i])
            pass
        #----------Add to the buffer all the pairs of (word, index)----------#
 
 
        #-------------------Add to the buffer the children-------------------#
        for child in self.children:
            buffer += struct.pack("i", child)
            pass
        #-------------------Add to the buffer the children-------------------#
 
        #Add the page.
        buffer += struct.pack("i", self.page)
 
        #Add the parent.
        buffer += struct.pack("i", self.parent)
 
        #Fill the remaining space with spaces.
        for i in range( self.uselessBytes ):
            buffer += str.encode(" ")
            pass
 
        #Write the buffer and return the
        #number of bytes written.
        return file.write(buffer)
    #==================================Write==================================#
 
 
 
 
    #==================================Read===================================#
    def read(self, file, page):
 
        #Seek into the file.
        file.seek(self.bufferSize * page)
 
        #Create the buffer.
        buffer   = file.read(self.bufferSize)
 
 
        #----------Get the (word, index) pairs----------#
        counter  = 0
        for i in range(0, self.totalAmountOfKeys * 16, 16):
            self.word [counter] = bytes.decode( buffer[i:i+12] )
            self.index[counter] = struct.unpack("i", buffer[i+12:i+16] ) [0]
            counter += 1
            pass
        #----------Get the (word, index) pairs----------#
 
 
 
        #----------------Get the children---------------#
        counter    = 0
        start      = self.totalAmountOfKeys * 16
        end        = start + self.maxChildren * 4
        for i in range(start, end, 4):
            self.children[counter] = struct.unpack("i", buffer[i:i+4] )[0]
            counter += 1
            pass
        #----------------Get the children---------------#
 
 
        #Get page and parent.
        self.page   = struct.unpack("i", buffer[end:end+4])[0]
        self.parent = struct.unpack("i", buffer[end+4:end+8])[0]
 
        #Return the amount of readen bytes.
        return len(buffer)
    #==================================Read===================================#
 
 
 
 
 
    #=================================Is Leaf=================================#
    def isLeaf(self):
        '''Returns True, if the node is a leaf.'''
 
        for child in self.children:
            if child != -1 : return False
 
        return True
    #=================================Is Leaf=================================#
 
 
 
 
    #=================================Is Full=================================#
    def isFull(self):
        '''Returns True, if the node is full of children.'''
 
        for child in self.children:
            if child == -1 : return False
 
        return True
    #=================================Is Full=================================#
 
 
 
 
    #==================================Print==================================#
    def print(self):
        '''This method is for debugging.'''
 
        print("Is Leaf\t\t:",self.isLeaf())
        print("Is Full\t\t:",self.isFull())
        print("Page\t\t:",self.page)
        print("Parent\t\t:",self.parent)
        print("Keys\t\t:",self.totalAmountOfKeys)
        print("Max Children\t:",self.maxChildren)
        print("Useless Bytes\t:",self.uselessBytes)
 
        print()
        for i in range( self.totalAmountOfKeys ):
            print("Word["+str(i)+"]:",self.word[i],", Index["+str(i)+"]:",self.index[i])
            pass
 
        print()
        for i in range( self.maxChildren ):
            print("Child["+str(i)+"]:",self.children[i])
            pass
 
        return
    #==================================Print==================================#

class Test:
    petros = ""

class Test:
    pass
 
obj = Test()
obj.petros = ""

>>> class A:
	class_att=4
 
 
>>> c=A()
>>> c.class_att
4
>>> c.__dict__
{}
>>> c.class_att=4
>>> c.__dict__
{'class_att': 4}

private int i=5;