How to control the LineEdit enabled by other conditions

[kafpost]

Hi,the lineEdit can be enabled by the RadioButton checked. Is there any other expressions or statements to enable the lineEdit not just the RadioButton checked. Thanks !

[lxn]

For this you can use any expression evaluating to a boolean value.

Walk currently uses https://gopkg.in/Knetic/govaluate.v3 to support evaluating expressions specified with the declarative.Bind function.

For examples of supported expressions have a look at this tests.

Also check the widget structs in the declarative sub package of walk to find fields of type declarative.Property, which you can use in your expressions.

AFAIK there are currently only two examples in Walk, that make use of this feature.

The databinding example uses a named DataBinder to be able to refer to its DataSource in an expression:

...
    Dialog{
        AssignTo:      &dlg,
        Title:         Bind("'Animal Details' + (animal.Name == '' ? '' : ' - ' + animal.Name)"),
        DefaultButton: &acceptPB,
        CancelButton:  &cancelPB,
        DataBinder: DataBinder{
            AssignTo:       &db,
            Name:           "animal",
            DataSource:     animal,
            ErrorPresenter: ToolTipErrorPresenter{},
        },
...

The webview example uses a function to choose an icon depending on the current URL:

...
    MainWindow{
        Icon:    Bind("'../img/' + icon(wv.URL) + '.ico'"),
        Title:   "Walk WebView Example'",
        MinSize: Size{800, 600},
        Layout:  VBox{MarginsZero: true},
        Children: []Widget{
            LineEdit{
                AssignTo: &le,
                Text:     Bind("wv.URL"),
                OnKeyDown: func(key walk.Key) {
                    if key == walk.KeyReturn {
                        wv.SetURL(le.Text())
                    }
                },
            },
            WebView{
                AssignTo: &wv,
                Name:     "wv",
                URL:      "https://github.com/lxn/walk",
            },
        },
        Functions: map[string]func(args ...interface{}) (interface{}, error){
            "icon": func(args ...interface{}) (interface{}, error) {
                if strings.HasPrefix(args[0].(string), "https") {
                    return "check", nil
                }

                return "stop", nil
            },
        },
    }.Run()
...

Additionally to the Functions map, there is an Expressions map in declarative.Composite, declarative.Dialog and declarative.MainWindow, which you can add your own custom expressions to. Have a look at https://github.com/lxn/walk/blob/master/condition.go.