On Wednesday 19 October 2005 1:17 am, David Boddie wrote:
> On Tue, 18 Oct 2005 18:24:08, Phil Thompson wrote:
> > I'm wondering whether QString should be dropped in PyQt4 in order to make
> > it more Pythonic.
>> On one hand, it sounds like a nice idea. It would mean that you don't
> have to think about manually converting the ones you think you'll need
> and keeping track of the ones you don't. On the other hand, the idea of
> dropping it makes me feel uneasy for reasons I'll talk about below.
>> > At the moment Python strings and unicode strings are automatically
> > converted to QStrings when passed as arguments - so there would be no
> > change there. If a QString was returned by a method or an operator then a
> > unicode string would be returned instead.
> >
> > Obviously you would lose all of QString's methods and would have to rely
> > on what Python gives you for manipulating strings.
>> I took another look at the QString API in Qt 4 to see whether this would be
> all that bad. There are a few functions there that provide in-place
> operations on strings and, although there are no exact equivalents for
> Python strings, they probably aren't all that relevant in Python.
> The same is possibly true of conversion functions like toDouble() and
> fromDouble().
>> > One of the limitations of QString has been that you couldn't do...
> >
> > q = "Py" + QString("Qt")
> >
> > ...but with current snapshots you can - so this is an argument for
> > keeping QString as it has become easier to use.
>> Yes, this is much better.
>> > BTW, the following is a consequence of the additional support...
> >
> > s = "Py"
> > # s is of type str
> > s += QString("Qt")
> > # s is now of type QString
>> This looks strange, but makes some kind of sense if you consider QString
> to be a more general string type than Python strings.
It's standard Python behaviour, it's not something I've specifically
implemented. As Gerard pointed out the same happens with ints and floats.
> > Comments, opinions welcome.
>> There are a few areas where we'd need to think about the consequences
> a bit more, or at least try experimenting with a Pythonic implementation,
> before deciding whether the suggested behaviour would be an improvement.
>> Off the top of my head, I think we should consider the following things:
>> * Translation with tr() - would it return a QString or a Python
> unicode string?
QString just wouldn't exist in PyQt4.
> * The types of arguments emitted with signals and the types of values
> received in slots - declaring arguments as "const QString &" then
> getting a unicode string might be a bit confusing.
This isn't specific to QString - it applies to anything implemented as a
%MappedType, ie. it's an existing issue. Whether PyQt4 should take Python
types in signal signatures is another debate...
> * Maintenance of QStrings passed to Python implemented methods - sometimes
> it's good to keep things in the same form that they were supplied in,
> although maybe it's not as important for QStrings as it is for, say,
> QImages.
Examples? It would be possible to add an annotation to SIP, something
like /GetWrapper/ so that %MethodCode could be given the C++ address as a
void *.
> * Codecs - does Python support the same range of codecs as Qt?
As a mono-lingual Brit, that's one of my implied questions - is Python's
unicode support good enough to be used instead of Qt's?
> * QLatin1String and other "restricted" string types - these are something
> of an implementation detail, but it's worth thinking about how these
> would be represented.
They wouldn't be wrapped.
> It would be also interesting to consider whether QStrings could be cached
> to avoid lots of copying between QString and unicode objects.
While it's easy enough to create a sub-type of the Python unicode type that
keeps an optional QString copy, I can't see how to make it any easier to use
than QString. You'd have to create it with some sort of ctor. The alternative
approach of keeping a separate map of string/unicode objects to QStrings
gives you problems with garbage collecting the map. (Python string/unicode
objects don't support weak references.)
> Personally, I don't see the problem with having strings arrive in Python
> functions or methods as unicode objects, but I'd like to see QString kept
> around for familiarity.
>> I think that there are two groups of people who expect different things,
> and QString is possibly controversial to many people because it's peculiar
> to see a class that duplicates the functionality of a built-in type.
> However, I think that there's an advantage in being able to write code in
> Python that resembles what you would write in C++. This applies to other
> classes that would appear to duplicate Python built-in types.
I've always promoted PyQt's use as a rapid prototyping tool where you
eventually re-write the prototype in C++ - but I'm not convinced that anybody
actually does this. With the availability of GPL Qt for Windows I hope/expect
that there will be many new users for PyQt4 (new to Python as well as new to
Qt, and with no experience of C++) so eliminating C++isms is more important
to me now than it has been in the past.
Phil
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‘She has never mentioned her father to me. Was he—well, the sort of man whom the County Club would not have blackballed?’ "We walked by the side of our teams or behind the wagons, we slept on the ground at night, we did our own cooking, we washed our knives by sticking them into the ground rapidly a few times, and we washed our plates with sand and wisps of grass. When we stopped, we arranged our wagons in a circle, and thus formed a 'corral,' or yard, where we drove our oxen to yoke them up. And the corral was often very useful as a fort, or camp, for defending ourselves against the Indians. Do you see that little hollow down there?" he asked, pointing to a depression in the ground a short distance to the right of the train. "Well, in that hollow our wagon-train was kept three days and nights by the Indians. Three days and nights they stayed around, and made several attacks. Two of our men were killed and three were wounded by their arrows, and others had narrow escapes. One arrow hit me on the throat, but I was saved by the knot of my neckerchief, and the point only tore the skin a little. Since that time I have always had a fondness for large neckties. I don't know how many of the Indians we killed, as they carried off their dead and wounded, to save them from being scalped. Next to getting the scalps of their enemies, the most important thing with the Indians is to save their own. We had several fights during our journey, but that one was the worst. Once a little party of us were surrounded in a small 'wallow,' and had a tough time to defend ourselves successfully. Luckily for us, the Indians had no fire-arms then, and their bows and arrows were no match for our rifles. Nowadays they are well armed, but there are[Pg 41] not so many of them, and they are not inclined to trouble the railway trains. They used to do a great deal of mischief in the old times, and many a poor fellow has been killed by them." As dusk came on nearly the whole population of Maastricht, with all their temporary guests, formed an endless procession and went to invoke God's mercy by the Virgin Mary's intercession. They went to Our Lady's Church, in which stands the miraculous statue of Sancta Maria Stella Maris. The procession filled all the principal streets and squares of the town. I took my stand at the corner of the Vrijthof, where all marched past me, men, women, and children, all praying aloud, with loud voices beseeching: "Our Lady, Star of the Sea, pray for us ... pray for us ... pray for us ...!" It had not occurred to her for some hours after Mrs. Campbell had told her of Landor's death that she was free now to give herself to Cairness. She had gasped, indeed, when she did remember it, and had put the thought away, angrily and self-reproachfully. But it returned now, and she felt that she might cling to it. She had been grateful, and she had been faithful, too.[Pg 286] She remembered only that Landor had been kind to her, and forgot that for the last two years she had borne with much harsh coldness, and with a sort of contempt which she felt in her unanalyzing mind to have been entirely unmerited. Gradually she raised herself until she sat quite erect by the side of the mound, the old exultation of her half-wild girlhood shining in her face as she planned the future, which only a few minutes before had seemed so hopeless. After he had gloated over Sergeant Ramsey, Shorty got his men into the road ready to start. Si placed himself in front of the squad and deliberately loaded his musket in their sight. Shorty took his place in the rear, and gave out: The groups about each gun thinned out, as the shrieking fragments of shell mowed down man after man, but the rapidity of the fire did not slacken in the least. One of the Lieutenants turned and motioned with his saber to the riders seated on their horses in the line of limbers under the cover of the slope. One rider sprang from each team and ran up to take the place of men who had fallen. "As long as there's men and women in the world, the men 'ull be top and the women bottom." Then, in the house, the little girls were useful. Mrs. Backfield was not so energetic as she used to be. She had never been a robust woman, and though her husband's care had kept her well and strong, her frame was not equal to Reuben's demands; after fourteen years' hard labour, she suffered from rheumatism, which though seldom acute, was inclined to make her stiff and slow. It was here that Caro and Tilly came in, and Reuben began to appreciate his girls. After all, girls were needed in a house—and as for young men and marriage, their father could easily see that such follies did not spoil their usefulness or take them from him. Caro and Tilly helped their grandmother in all sorts of ways—they dusted, they watched pots, they shelled peas and peeled potatoes, they darned house-linen, they could even make a bed between them. HoME一级毛片视频免费公开
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