The purpose of the
meterValueHolder instance variable is to provide
a place for the value holder that is to hold the value shown on the meter.
As explained in Segment 831, the initial value of that instance
variable is established by the
meterValueHolder getter. That
initial value is an initialized value holder:
MeterDemonstration method definition instance meterValueHolder ^ meterValueHolder isNil ifTrue: [meterValueHolder := 5 asValue] ifFalse: [meterValueHolder]