On Feb 12, 11:53 am, maksym.ka...@gmail.com wrote: > Hi there. > now i'm a complete newbie for python, and maybe my problem is stupid > but i cannot solve it myself > > i have an object of class GeoMap which contains lists with objects of > GeoMapCell (i will not explain what they should do, hope its not > important). Then i want to serialize these objects to json notation. > So i imported json module and as shown in docs for it extended > JSONEncoder class. Look at the code below > > ##main module > from worldmap import GeoMap, GeoMapCell > > import testdata > import json > > class GeoMapEncoder(json.JSONEncoder): > def default(self, obj): > if isinstance(obj, GeoMap): > return None > return json.JSONEncoder.default(self, obj) > > def main(): > print(json.dumps(2 + 5j, cls=ComplexEncoder)) > > geomap = testdata.createTestMap() > print(json.dumps(geomap, cls=GeoMapEncoder)) > pass > > if __name__ == '__main__': > main() > > =========== > > ##worldmap module > class GeoMap: > cells = [] > activerow = 0 > activecol = 0 > > def addCell(self, acell): > if len(self.cells) == 0: > self.cells.append([]) > self.activerow = 0 > acell.col = self.activerow > acell.row = self.activecol > self.cells[self.activerow].append(acell) > self.activecol += 1 > > def addRow(self): > self.cells.append([]) > self.activerow += 1; > self.activecol = 0; > > class GeoMapCell: > neighbours = (None, None, None, None, None, None, ) > col = 0 > row = 0 > > The problem is in here. > > class GeoMapEncoder(json.JSONEncoder): > def default(self, obj): > if isinstance(obj, GeoMap): ## <======= isinstance doesnot > work as i expected > return None > return json.JSONEncoder.default(self, obj) > > Though obj is object of GeoMap class, isinstance returns False. Where > was i mistaken. If i shouldn't use isinstance, then what function > would check class of object? > > Oh, maybe its important. I'm working on WinXP SP3, Python 3.0, IDE - > PyScript
Here's a crazy idea out of left field. Just before calling isinstance, why not try: print(type(obj)) print(str(obj)) This may illuminate the unexpected behavior, you'll find out just what obj has in it. -- Paul -- http://mail.python.org/mailman/listinfo/python-list
