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{alias:qtrace} |
Name
qtrace — connect widget and Tcl variable
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Assigning a value to a trace-variable may result in the corresponding widgets callback function being called. Use qblockedtrace to create a trace variable without this effect. |
Arguments
widget
The widget
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to which the variable will be connected. If this argument is omitted the current widget will be used. This must be an instance of qlineedit, qlabel, qtextedit, [QTextEdit, qcheckbox, qradiobutton, qspinbox, qdoublespinbox, qhslider, and qvslider.
variable
The name of the variable. The variable should be global or exist in a namespace. When referring to a namespace variable the namespace name should be part of the argument, like "MyNamespace::my_variable".
Examples
Ex.1: QTrace
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set w [qwidget ]
qsetwindowtitle "Variable tracing"
# Create text editor and "Show Text" button.
set layout [qhboxlayout $w]
set label [qlabel "First Name :"]
qaddwidget $layout $label
set lineedit [qlineedit]
qaddwidget $layout $lineedit
# Connect contents of line edit to variable 'name'
qtrace $lineedit name
# Set Tcl variable - this will automatically set the
# text in the line edit to 'Jon'
set name Jon
qshow $w
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