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| Functions: passing a shelf as a modifiable argument | |||||
| Prerequisite Concepts | Related Syntax | ||||
A modifiable argument is also a reference to an existing shelf. It is modifiable because the called function can modify the passed shelf in any of the ways that shelves can be modified (as long as the original shelf permits the operation). A modifiable shelf can have the key or value of any of its items changed, and clear, new, and the copy action can be used on it as well.
A modifiable argument is used in preference to a read-only one when the argument is used to return results. It is useful when the single result value that can be returned from a function is not sufficient -- for example, where more than one value needs to be returned.
An item on a modifiable argument shelf can be passed to another function individually as a value argument, or as part of a remainder argument. The entire shelf can be passed as either a read-only argument or as a modifiable argument.
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Prerequisite Concepts Functions Functions: argument classes Functions: argument shelf types |
Related Syntax define function |
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