Unset Variable Representations
- Last UpdatedFeb 08, 2023
- 1 minute read
Each new data type supports a String() method that returns a string representing the value of the variable. For example:
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!X = 2.5 |
$* defines a variable X of type REAL with 2.5 as its numeric value |
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!S = !X.String() |
$* will be a variable of type STRING, with the value "2.5" |
UNSET variables of all built-in data types have an unset representation:
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!X = REAL()! S = !X.String() |
$* yields the string ’(the empty string) |
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!X = BOOLEAN() !S = !X.String() |
$* yields the string ‘’ (the empty string) |
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!X = STRING() !S = !X.String() |
$* yields the string ‘Unset’ |
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!X = ARRAY() !S = !X.String() |
$* yields the string ‘ARRAY’ |
Other variable types are system-defined variables. Most of these have adopted the unset string ‘Unset’. For example:
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!X = DIRECTION() !S = !X.String() |
$* yields the string ‘Unset’ |
User-defined data types can also provide a String() method. These also support an UNSET representation, and usually adopt the UNSET representation ‘Unset’.