I started learning PyQt from zetcode, as far as i know sys.argv reads in the parameter from coomandline and first being the name of file itself, so if sys.argv is a list then what being passed to QtGui.QApplication() in
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
Because this call invokes an underlying C++ function which uses argv and doesn't know about python. Qt understand a set of command line arguments, see here for example.
ok then what is in the sys.argv list ?
Here is an example program
#!/usr/bin/env python
# testargv.py
if __name__ == "__main__":
import sys
print(sys.argv)
"""my command line -->
testargv.py -foo bar --baz qux -o foobar.txt bazqux.pdf
my output -->
['./testargv.py', '-foo', 'bar', '--baz', 'qux', '-o', 'foobar.txt', 'bazqux.pdf']
"""
sys.argv is the list of command line arguments that were given to the program.
well i do understand that what would it be incase of app = QtGui.QApplication(sys.argv)
Let's give it a try:
import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *
app = QApplication(sys.argv)
# ----- start your widget test code ----
# create the label
label = QLabel()
label.show()
# insert a text string
label.setText('Hello fron DaniWeb!')
print(sys.argv)
# ---- end of widget test code -----
app.exec_()
''' my console output -->
['C:\\Python33\\BS\\pqt_sys_argv.py']
'''
QApplication() expects a list, but you can feed it an empty list if you don't want to putz around with sys.argv
from PyQt4.QtCore import *
from PyQt4.QtGui import *
app = QApplication([])
# ----- start your widget test code ----
# create the label
label = QLabel()
label.show()
# insert a text string
label.setText('Hello fron DaniWeb!')
# ---- end of widget test code -----
app.exec_()
nice thanks, i am learning now, i think it would good if i buy book though.. however now another question strikes, i cant avoid asking back so here it goes, if QApplication() expects a list, and we can pass in [] empty list then why sys.argv is used in every tutorial of zetcode, like Gribouillis said why not pass the -style "motif"... ?
why not pass the -style "motif"... ?
I tried sneekula's code with -widgetcount and it worked as described in the doc. The best thing to do is to run your code with various arguments and see what it does.
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