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Jay

Tue Feb 22, 2005 10:58 am


Default values for function?

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Hey all, I've google'd and searched all this forum, and now I'm finally desperate and posting. Is there any way in Turing to have default values for a function's parameters? I can't find anything that points one way or the other, but I figure if I haven't found anything by now there's probably no way. I also wanted to use function overloading, but found a thread that confirms that that's not possible.

Thanks.


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Tony

Tue Feb 22, 2005 1:42 pm



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there's a way to fake function overload in Turing. You'd have to use pointers to functions and when you want to overload something, just change the pointer to a new function. Should work.

As for default values : there're two approaches to the problem.

1) make all of arguments be string, and if NULL ("") is passed, you make it a default value instead. For integers and floats you can use strint() and strreal().

function foo (bar : string) : string
    if bar not= "" then
        result bar
    else
        result "default"
    end if
end foo

put foo ("bar")
put foo ("")


2) Might be a more interesting approach: accepting an array of arguments. The size will be flexable, it is actually possible to incorporate multiple constructors for the same function.. (hardcoded overloading?)

function foo (bar : array 0 .. * of string) : string
    var out : array 0 .. 4 of string := init ("1", "2", "3", "4", "5")
    var answer : string := ""
    if upper (bar) not= 0 then %atleast one argument has been passed
        for i : 0 .. upper (bar)
            out (i) := bar (i)
        end for
    end if

    for i : 0 .. upper (out)
        answer += out (i) + " :: "
    end for

    result answer
end foo

var myArguments1 : array 0 .. 0 of string := init ("")
put foo (myArguments1)
var myArguments2 : array 0 .. 1 of string := init ("Tony", "Dan")
put foo (myArguments2)
var myArguments3 : array 0 .. 4 of string := init ("Tony", "Dan", "Martin", "compsci", "Ruby")
put foo (myArguments3)



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Jay

Tue Feb 22, 2005 4:41 pm



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Thanks for the help.