[Development] About ALIAS in Q_PROPERTY
Svetkin Mikhail
mikhail.svetkin at gmail.com
Tue Mar 11 12:13:43 CET 2014
I don't understand what do you mean exactly, please explain in details.
2014-03-11 16:05 GMT+06:00 Konstantin Ritt <ritt.ks at gmail.com>:
> 2014-03-11 11:57 GMT+02:00 Svetkin Mikhail <mikhail.svetkin at gmail.com>:
>
> Try initializing that `ui` with 0 and see what happens.
>>
>> For this, in moc(for ALIAS) can add a check
>>
>
> You can not.
>
>
>>
>> Q_PROPERTY(QString label ALIAS AnyCrap
>>> m_parent->labelWidget->objectName())
>>
>>
>> This example not valid.
>>
>> Q_PROPERTY(QString label ALIAS AnyCrap
>> m_parent->labelWidget->propertyName).
>>
>> Where `propertyName` link on Q_PROPERTY(type propertyName)
>>
>> If the syntax is very complex, it is possible to do so
>> Q_PROPERTY(QString label ALIAS AnyCrap m_parent->labelWidget
>> propertyName).
>>
>> 2014-03-11 15:12 GMT+06:00 Konstantin Ritt <ritt.ks at gmail.com>:
>>
>> Try initializing that `ui` with 0 and see what happens.
>>>
>>> Similar for using the property from a destructor or destruction
>>> sequence, since moc is unable to track the pointers in use.
>>> Also think about objects you don't control, i.e. Q_PROPERTY(QString
>>> label ALIAS AnyCrap m_parent->labelWidget->objectName()) ...and so on.
>>>
>>> Regards,
>>> Konstantin
>>>
>>>
>>> 2014-03-11 10:59 GMT+02:00 Svetkin Mikhail <mikhail.svetkin at gmail.com>:
>>>
>>> Why do you think moc will crash?
>>>>
>>>>
>>>> 2014-03-11 14:30 GMT+06:00 Konstantin Ritt <ritt.ks at gmail.com>:
>>>>
>>>>> > Would suggest to solve this problem in this way(The code marked as
>>>>> duplicate does not need anymore.):
>>>>> > Q_PROPERTY(QString <http://qt-project.org/doc/QString.html> label
>>>>> ALIAS CustomWidgetFirst ui->custom_widget_first_obj->value ) //
>>>>> where "value" property name
>>>>>
>>>>> I don't think moc is able to guarantee no crash at
>>>>> `ui->custom_widget_first_obj->value`. So you're trading safety for nothing.
>>>>>
>>>>> Konstantin
>>>>>
>>>>>
>>>>> 2014-03-11 5:12 GMT+02:00 Svetkin Mikhail <mikhail.svetkin at gmail.com>:
>>>>>
>>>>> Explain:
>>>>>> I was creating custom widgets with the help of Qt-designer.
>>>>>> And I have noticed I have to duplicate my code, if I want to edit
>>>>>> properties of the widget in qt-designer property editor.
>>>>>> Simple Example:
>>>>>>
>>>>>>
>>>>>> 1. // custom_widget_first.h
>>>>>> 2.
>>>>>> 3. #include <QWidget>
>>>>>> 4. #include <QString>
>>>>>> 5. #include <QPaintEvent>
>>>>>> 6.
>>>>>> 7. class CustomWidgetFirst : public QWidget<http://qt-project.org/doc/QWidget.html>
>>>>>> {
>>>>>> 8. Q_OBJECT
>>>>>> 9. Q_PROPERTY(QString <http://qt-project.org/doc/QString.html> value
>>>>>> READ label WRITE setLabel)
>>>>>> 10. public:
>>>>>> 11. explicit CustomWidgetFirst(QWidget<http://qt-project.org/doc/QWidget.html>
>>>>>> *parent = 0)
>>>>>> 12. ~CustomWidgetFirst();
>>>>>> 13.
>>>>>> 14. QString <http://qt-project.org/doc/QString.html> label()
>>>>>> const;
>>>>>> 15. void setLabel(const QString<http://qt-project.org/doc/QString.html>
>>>>>> &label);
>>>>>> 16.
>>>>>> 17. protected:
>>>>>> 18. void paintEvent(QPaintEvent<http://qt-project.org/doc/QPaintEvent.html>
>>>>>> *event);
>>>>>> 19.
>>>>>> 20. private:
>>>>>> 21. QString <http://qt-project.org/doc/QString.html> m_label;
>>>>>> 22. };
>>>>>> 23.
>>>>>> 24. // custom_widget_first.cpp
>>>>>> 25.
>>>>>> 26. #include "custom_widget_first.h"
>>>>>> 27.
>>>>>> 28. CustomWidgetFirst::CustomWidgetFirst(QWidget<http://qt-project.org/doc/QWidget.html>
>>>>>> *parent)
>>>>>> 29. : QWidget <http://qt-project.org/doc/QWidget.html>(parent) {
>>>>>> 30. }
>>>>>> 31.
>>>>>> 32. QString <http://qt-project.org/doc/QString.html>
>>>>>> CustomWidgetFirst::label() const {
>>>>>> 33. return m_label;
>>>>>> 34. }
>>>>>> 35.
>>>>>> 36. void CustomWidgetFirst::setLabel(const QString<http://qt-project.org/doc/QString.html>
>>>>>> &label) {
>>>>>> 37. m_label = label;
>>>>>> 38. }
>>>>>> 39.
>>>>>> 40. void CustomWidgetFirst::paintEvent(QPaintEvent<http://qt-project.org/doc/QPaintEvent.html>
>>>>>> *event) {
>>>>>> 41. // some paint
>>>>>> 42. }
>>>>>> 43.
>>>>>> 44. CustomWidgetFirst::~CustomWidgetFirst() {
>>>>>> 45. }
>>>>>> 46.
>>>>>> 47. // custom_widget_second.h
>>>>>> 48.
>>>>>> 49. #include <QWidget>
>>>>>> 50. #include <QString>
>>>>>> 51.
>>>>>> 52. namespace Ui {
>>>>>> 53. class Form;
>>>>>> 54. }
>>>>>> 55.
>>>>>> 56. class CustomWidgetSecond : public QWidget<http://qt-project.org/doc/QWidget.html>
>>>>>> {
>>>>>> 57. Q_OBJECT
>>>>>> 58. Q_PROPERTY(QString <http://qt-project.org/doc/QString.html>
>>>>>> text
>>>>>> 59. READ getUiCustomWidgetSecondTextLabel
>>>>>> 60. WRITE setUiCustomWidgetSecondTextLabel)
>>>>>> 61.
>>>>>> 62. public:
>>>>>> 63. explicit CustomWidgetSecond(QWidget<http://qt-project.org/doc/QWidget.html>
>>>>>> *parent = 0)
>>>>>> 64. ~CustomWidgetSecond();
>>>>>> 65.
>>>>>> 66. QString <http://qt-project.org/doc/QString.html>
>>>>>> getUiCustomWidgetFirstLabel() const; // dublicate
>>>>>> code
>>>>>> 67. void setUiCustomWidgetFirstTextLabel(const QString<http://qt-project.org/doc/QString.html>
>>>>>> &text); // dublicate code
>>>>>> 68.
>>>>>> 69. private:
>>>>>> 70. Ui::Form *ui; // ui generated from uic and have several
>>>>>> widgets, including CustomWidgetFirst
>>>>>> 71. };
>>>>>> 72.
>>>>>> 73. // custom_widget_second.cpp
>>>>>> 74.
>>>>>> 75. #include "custom_widget_second.h"
>>>>>> 76. #include "ui_form.h"
>>>>>> 77.
>>>>>> 78. CustomWidgetSecond::CustomWidgetSecond(QWidget<http://qt-project.org/doc/QWidget.html>
>>>>>> *parent)
>>>>>> 79. : QWidget <http://qt-project.org/doc/QWidget.html>(parent),
>>>>>> 80. ui(new Ui::Form) {
>>>>>> 81. ui->setupUi(this);
>>>>>> 82. }
>>>>>> 83.
>>>>>> 84. QString <http://qt-project.org/doc/QString.html>
>>>>>> CustomWidgetSecond::getUiCustomWidgetFirstTextLabel() const { //
>>>>>> duplicate code
>>>>>> 85. return ui->CustomWidgetFirst->label();
>>>>>> // duplicate code
>>>>>> 86. }
>>>>>> // duplicate code
>>>>>> 87.
>>>>>> 88. void CustomWidgetSecond::setUiCustomWidgetFirstTextLabel(const
>>>>>> QString <http://qt-project.org/doc/QString.html> &text) { //
>>>>>> duplicate code
>>>>>> 89. ui->CustomWidgetFirst->setLabel(text);
>>>>>> // duplicate code
>>>>>> 90. }
>>>>>> // duplicate code
>>>>>> 91.
>>>>>> 92. CustomWidgetSecond::~CustomWidgetSecond() {
>>>>>> 93. delete ui;
>>>>>> 94. }
>>>>>>
>>>>>>
>>>>>> Would suggest to solve this problem in this way(The code marked as
>>>>>> duplicate does not need anymore.):
>>>>>>
>>>>>> 1. Q_PROPERTY(QString <http://qt-project.org/doc/QString.html> label
>>>>>> ALIAS CustomWidgetFirst ui->custom_widget_first_obj->value ) //
>>>>>> where "value" property name
>>>>>>
>>>>>> The ALIAS attribute indicates that the property will be reference on
>>>>>> another
>>>>>> property. If ALIAS property has a signal, you need to declare the
>>>>>> same signal
>>>>>> because moc will automatically generate connect(aliasObject,
>>>>>> aliasSignal, yourClassObject, aliasSignal)
>>>>>> and you will only need call initAliasNotify function in the class
>>>>>> construct.
>>>>>>
>>>>>>
>>>>>> 2014-03-10 22:43 GMT+06:00 Giuseppe D'Angelo <dangelog at gmail.com>:
>>>>>>
>>>>>> Can you please explain what this feature is about, why do you think
>>>>>>> it's useful, how it's supposed to be used, etc.?
>>>>>>>
>>>>>>> On 10 March 2014 17:30, mikhail.svetkin at gmail.com
>>>>>>> <mikhail.svetkin at gmail.com> wrote:
>>>>>>> > Hello, I would like to clarify wherein the complexity
>>>>>>> > (https://codereview.qt-project.org/#change,80412)?
>>>>>>> > Ready to listen to any suggestions and implement them.
>>>>>>> >
>>>>>>> > --
>>>>>>> > Mikhail Svetkin
>>>>>>> > _______________________________________________
>>>>>>> > Development mailing list
>>>>>>> > Development at qt-project.org
>>>>>>> > http://lists.qt-project.org/mailman/listinfo/development
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Giuseppe D'Angelo
>>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Development mailing list
>>>>>> Development at qt-project.org
>>>>>> http://lists.qt-project.org/mailman/listinfo/development
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/development/attachments/20140311/34c3b491/attachment.html>
More information about the Development
mailing list