[FIXED] Qt: Potential side-effects of Layout?

Issue

from PySide.QtGui import *
import sys

app = QApplication(sys.argv)
layout = QHBoxLayout()
print issubclass(type(layout), QWidget)
# Layout is not a kind of QWidget

window = QWidget()
window.resize(500, 500)
window.show()
window.setLayout(layout)

butt = QPushButton("asdf", parent = None)
butt.resize(100, 100)
butt.show()
layout.addWidget(butt)

print butt.parent() 

app.exec_()

The parent object of butt is window in fact. But I haven't set its parent to window explicitly. Can I say that the Layout Object has some side effects which may set the added widget's parent to the container that it applied to?

Solution

Yes.

Relevant part from the docs:

When you use a layout, you do not need to pass a parent when constructing the child widgets. The layout will automatically reparent the widgets (using QWidget::setParent()) so that they are children of the widget on which the layout is installed.

Note: Widgets in a layout are children of the widget on which the layout is installed, not of the layout itself. Widgets can only have other widgets as parent, not layouts.

Answered By - Avaris