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Hwa Jong Oh,
> What does the type converter aspect do for an TextEdit?
It allows you to convert from the text format that the TextPresenter handles
to another type of object (an instance of another Smalltalk class).
Evaluate
t := TextPresenter create.
t view topView extent: 200@60.
t view show
and enter a date into the text edit in your normal format - 15/12/2000 in my
case. Inspect the following and you will see that the TextPresenter answers,
not unsurprisingly, a String.
t value
Now evaluate the following, re-enter the date, inspect the value again and
you should now get an instance of the Date subclass. The typeconverter has
automatically converted the String for you.
t view typeconverter: DateToText new
It also works the other way. Evaluate
t := TextPresenter create.
t view topView extent: 200@60.
t view show.
t value: Date today
You can see that the TextPresenter (or rather the TextEdit>>displayValue
method) will display the Date in text correctly as it always sends
#displayString to the Date before passing it on to Windows. However, this
always uses the default display format, if you want a different format you
can use the TypeConverter.
t view typeconverter: DateToText new.
t view typeconverter format: 'yyyy/MMM/d'.
t value: Date today
You can also use TypeConverters outside of MVP as an easy way to perform
some common conversions
BooleanToText new convertFromRightToLeft: 'true'.
BooleanToText new convertFromRightToLeft: 'FALSE'.
BooleanToText new convertFromLeftToRight: false
The 'left' and 'right' bits refer to the position in the Class name - e.g.
in the above 'left' refers to the Boolean and 'right' refers to the Text
It is also illuminating that note that the _only_ major difference between a
"TextPresenter.Default view" resource and, for example, a
"DatePresenter.Text view" is that the latter defines a typeconverter.
Ian
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