python pickle模块的简单使用笔记

Python pickle 模块提供了把对象序列化的方法，对象会被序列化成ASCII的字符串，能够保存到文件。unpickle则能够从文件或字符中反序列化成对象。以下的两个方法很是有用。

pickle. dumps ( obj[, protocol] )

Return the pickled representation of the object as a string, instead of writing it to a file.

If the protocol parameter is omitted, protocol 0 is used. If protocol is specified as a negative value or HIGHEST_PROTOCOL, the highest protocol version will be used.

Changed in version 2.3: The protocol parameter was added.

pickle. loads ( string )

Read a pickled object hierarchy from a string. Characters in the string past the pickled object’s representation are ignored.

 

我在使用wx时，wxGrid的GetCellValue方法只能返回字符串。但我但愿它能够返回我定义的对象，因而我找到了pickle。我在类中重写__str__()方法，使用pickle来序列化这个对象。

例子：

import pickle
class LineProperty:
    def __init__(self, width=0, shape=0xFFFF, r=0, g=0, b=0, color=0):
        self.width = width
        self.shape = shape
        self.r = r
        self.g = g
        self.b = b
        self.color = color
    #使用pickle 序列化    
    def __str__(self):
        return pickle.dumps(self)

而后我在本身定义的wxGridTable中设置了这个数据，GridCellEditor中的重写的

BeginEditor方法

class LineGridCellEditor(grd.PyGridCellEditor):
    def Create(self, parent, id, evtHandler):
        self._control = wx.Control(parent, id, wx.DefaultPosition, (100, 100))
        self._parent = parent
        self.SetControl(self._control)
        
        newEvt = wx._core.EvtHandler()
        if newEvt:
            self._control.PushEventHandler(newEvt)
        self.startValue = self.endValue = None
        self.m_canvas = linecanvas.MyLineCanvas(self._control)
        
    def OnClick(self, evt):
        pass
    
    def Clone(self):
        return LineGridCellEditor()
        
    def BeginEdit(self, row, col, grid):
        self.startValue = grid.GetCellValue(row, col)

 
   
   
   
   
 
  

   
  
    
    
    
    
   
 
   
   
   
   
 
  
 
   
   
   
   
 
  

  
    
    
    
    
  
   
#在这里反序列化，传递给canvas
 
   
   
   
   
 
  
        self.m_canvas.SetScales(pickle.loads(str(self.startValue)))

这样就能够摆脱GetCellValue只能返回wxString的限制了。把对象传输过来，用glCanvas来绘制。