Depending on how you want the Checkbutton
to interact with the rest of your application, sometimes it makes
sense to use different values instead of 0 and 1. If you don’t
like the default value of 1, you can use the
-onvalue option to change it:
-onvalue => newvalue ## Default is 1
Similarly, if you want to use something
other than 0 for an off value, use -offvalue:
-offvalue => newvalue ## Default is 0The newvalue could be anything, as long as
it is a scalar value. This means you can use references to arrays and
hashes if you really want to.
It is good practice to keep the meaning of
-onvalue the opposite of
-offvalue. If -onvalue is now
the string "ON", logically
-offvalue should be "OFF". Of
course, if the purpose of this Checkbutton is to use a more accurate
value of pi, then -onvalue could be
"3.14159265359" and -offvalue
could be "3.14".
Be careful when you use unusual values for
-onvalue and -offvalue. If you
set the variable to something that doesn’t equal either one of
them, the Checkbutton will be considered off, even though the value
of the $variable will not equal the
-offvalue.For instance, if you
set -onvalue => 1, -offvalue =>
0, and you set $variable to 3, the
Checkbutton will be considered off.
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