object number -extends base {
    palettes "Inputs"
    help http://rappture.org/wiki/rp_xml_ele_number
    attr default -title "Default Value" -type string:validate=number -path default
    attr units -title "Units of Measurement" -type units -path units
    attr min -title "Minimum Value" -type string:validate=number -path min
    attr max -title "Maximum Value" -type string:validate=number -path max
    attr color -title "Color" -type color -path color

    check label {
        if {[string length [string trim $attr(label)]] == 0} {
            return [list warning "Should set a label that describes this value"]
        }
    }
    check description {
        set desc [string trim $attr(description)]
        if {[string length $desc] == 0} {
            return [list warning "Should include a description of what this value represents, typical settings, etc."]
        } elseif {[string equal $desc $attr(label)]} {
            return [list warning "Description should be different from the label and give additional information about the value."]
        }
    }

    check default {
        if {[string length [string trim $attr(default)]] == 0} {
            return [list error "Must have a default value for this number."]
        }
        if {"" != $attr(units)} {
            set base [Rappture::Units::System::for $attr(units)]
            if {[validate_number_parse $attr(default) num units]
               && "" != $units
               && ![string equal [Rappture::Units::System::for $units] $base]} {
                return [list error "Units for default value don't match the expected units for this value"]
            }

            set dval [Rappture::Units::convert $attr(default) -context $attr(units) -to $attr(units) -units off]

            if {[validate_number_parse $attr(min) num units]
                 && [catch {Rappture::Units::convert $attr(min) -context $attr(units) -to $attr(units) -units off} min] == 0
                 && $dval < $min} {
                return [list error "Default value is less than the minimum that you've specified for this value."]
            }

            if {[validate_number_parse $attr(max) num units]
                 && [catch {Rappture::Units::convert $attr(max) -context $attr(units) -to $attr(units) -units off} max] == 0
                 && $dval > $max} {
                return [list error "Default value is greater than the maximum that you've specified for this value."]
            }
        }
    }

    check min {
        if {"" != $attr(units)} {
            set base [Rappture::Units::System::for $attr(units)]
            if {[validate_number_parse $attr(min) num units]
               && "" != $units
               && ![string equal [Rappture::Units::System::for $units] $base]} {
                return [list error "Units for minimum value don't match the expected units for this value"]
            }
        }
        if {[catch {Rappture::Units::convert $attr(min) -context $attr(units) -to $attr(units) -units off} min] == 0
              && [catch {Rappture::Units::convert $attr(max) -context $attr(units) -to $attr(units) -units off} max] == 0
              && $min >= $max} {
            return [list error "Minimum value should be less than the maximum.  If you don't want to see a min/max range, you can clear out either or both values."]
        }
    }

    check max {
        if {"" != $attr(units)} {
            set base [Rappture::Units::System::for $attr(units)]
            if {[validate_number_parse $attr(max) num units]
               && "" != $units
               && ![string equal [Rappture::Units::System::for $units] $base]} {
                return [list error "Units for maximum value don't match the expected units for this value"]
            }
        }
    }
}