*** GMX Spamverdacht *** [PyQt] Questions about the PyQt examples

Andreas Pakulat apaku at gmx.de
Sun Mar 18 17:40:16 GMT 2007

On 18.03.07 22:28:12, Shriramana Sharma wrote:
> In the same #08, if I remove the word self from the line:
> self.emit(QtCore.SIGNAL("angleChanged(int)"), self.currentAngle)
> I get an error:
> Traceback (most recent call last):
>   File "./008.py.showserror-buthowdoesitwork", line 62, in setAngle
>     self . emit ( SIGNAL ( "angleChanged ( int )" ), currentAngle )
> NameError: global name 'currentAngle' is not defined
> But the program still works normally. How?

Because no object listens to the signal emitted here, thats IIRC
something that is used in a later tutorial.

> 4)
> In #02, the last but one line has a semicolon at the end. This is C
> syntax, not Python syntax. But still Python executes the program without
> any warning or error. How?

Read you python book again, a semicolon is proper Python syntax, but its
not necessary unless you want to put multiple statements onto the same

> 5)
> Why do the tutorials not use tr() for user visible strings?

Probably because the Qt translations are not covering the examples

> 6)
> I observed that a large part of the functions in the PyQt API take self
> as the first object (to emphasize that it should be called only on an
> instance of the class) but the calls in the examples do not include self
> as the first item. How is it that Python doesn't throw any errors?

Uhm, they do generally by doing self.foobar(). In that case Python calls

> 7)
> If there is no need to include "self", then why is it necessary to say
> "self" in the QWidget __init__ constructor whenever I subclass QWidget
> within PyQt?

See above it is necessary. 


Be cautious in your daily affairs.
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