[SOLVED] TypeError: 1st argument of QGridLayout.addWidget() must be a QGridLayout instance?

SatelliteEyes

Hi, I am going through the zetcode tutorial on layout management (http://zetcode.com/tutorials/pyqt4/layoutmanagement/) and I am getting a Type Error trying to use QGridLayout. I am using PyQt 4.4.4 and upgrading my version is not an option for a lot of annoying reasons that I cant control.

@...
def initUI(self):
names = ['Cls','Bck','','Close','7','8','9','/',
'4','5','6','*','1','2','3','-',
'0','.','=','+']

      grid = QtGui.QGridLayout

      j = 0
      pos = [(0,0),(0,1),(0,2),(0,3),
          (1,0),(1,1),(1,2),(1,3),
          (2,0),(2,1),(2,2),(2,3),
               (3,0),(3,1),(3,2),(3,3),
               (4,0),(4,1),(4,2),(4,3)]
        
      for i in names:
        print i, j
        button = QtGui.QPushButton(i)
        if j == 2:
            grid.addWidget(QtGui.QLabel(''),0,2)
        else: 
            grid.addWidget(button,pos[j][0],pos[j][1])
        j = j + 1

      self.setLayout(grid)
      self.move(300,150)
      self.setWindowtitle('Calculator')
      self.show()

@

When this runs I get an error: TypeError: first argument of unbound method QGridLayout.addWidget() must be a QGridLayout instance. If I set j = 2 to force

@
grid.addWidget(QtGui.QLabel(''),0,2)
@

to execute I get the same error.

I have no idea what this means. I haven't been able to find anyone on this or any other forum with the same error. My first argument is 'button' and it's a QPushButton instance. I've seen plenty of examples of people who've done very similar things. There is nothing in the documentation that suggests that the first argument must be a QGridLayout instance, only that it is a QWidget, which the QPushButton is.

Is this a problem with the way I've declared 'grid'?
Does QGridLayout create an matrix of boxes? Should I be iterating over grid as well as over names and pos?
Thoughts?

SGaist

Hi,

IIRC from my pythonic days, your grid object is not an instance of QGridLayout. You are simply missing a set of parenthesis

@grid = QtGui.QGridLayout()@

And you should be good

CAD_coding

I think creating widgets in stack memory is not a good idea especially if you have many of them.
I always create widgets in heap & manage the memory using QList<QWidget *>.
Personal preference though.

SGaist

@CAD_coding
Python and C++ do not handle data the same way. In python, there is no pointer.

CAD_coding

oops didnt know that ;)

SatelliteEyes

Thanks, @SGaist! Of course it would be something embarrassing like that once I've wracked my brains and finally decided to post!

SGaist

You're welcome !
Don't forget to set the thread's title as solved