ftp.cs.arizona.edu/ftp.cs.arizona.edu.tar/ftp.cs.arizona.edu/icon/newsgrp/group93c.txt/000042_icon-group-sender _Tue Sep 7 00:30:31 1993.msg

Internet Message Format | 1994-02-02 | 2KB

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Date: Tue, 7 Sep 93 00:30:31 -0700
From: "Nevin Jerome Liber" <nevin>
Message-Id: <[e-mail]>
To: [e-mail]
Subject: Re: return results from procedure
Status: R
Errors-To: [e-mail]

[e-mail] (Roger Hare) writes:

> I've been using Icon for seberal years now, but recently I stumbled across a
> 'problem' for the fist time - I wanted to return more than one result from a
> procedure (yup - strange to relate, after several years I had never needed to
> do this before).

> What I want to know is "what is the 'best' way to return several results from
> a procedure?'.

What I find most idiomatic for returning multiple results from a
procedure is to use generators.  The called routine would look like:

procedure MyProcedure()

    ...
    suspend xResult1
    ...
    suspend xResult2
    ...
    ...
    suspend xResultN
    ...

end

And the caller would look like:

...
every xElement := MyProcedure() do {
    ProcessElement(xElement)
}
...

This approach is space-efficient (if the data is being used in a FIFO
order, only one element has to be in existence at a given time) and
very flexible.  The caller, and not the callee can determine what type
of data structure to keep the elements in (unlike in more traditional
languages like C and Pascal).  For example, if I needed to build both an
ordered list and a set, I could write the caller like:

LList := list()
SSet := set()

every xElement := MyProcedure() do {
    put(LList, xElement)
    insert(SSet, xElement)
}
___
    Nevin ":-)" Liber    [e-mail]    [phone]