OpenEuphoria

Re: "Forward" function declarations?

• Posted by Michael Nelson <MichaelANelson at WORLDNET.ATT.NET> Feb 08, 2001
• 450 views

----- Original Message -----
From: "Ted Fines" <fines at macalester.edu>
To: <EUforum at topica.com>
Sent: Thursday, February 08, 2001 7:45 AM
Subject: "Forward" function declarations?


> I need to do the "C" equivalent of a "forward" function declaration in
> Euphoria.  Can this be done?
>

Not directly. A forward reference is illegal in Euphoria:

funcion foo(object x)
    integer z
    z=bar(x)  --syntax error "bar" not defined
    return z+2
end function

function bar(object y)
    if atom(y) return -1 else return length(y)
end function

printf(1,"%d",foo({1,2,3}))

and there is no way to declare a routine before it is defined (as there is
in C).  Instead Euphoria uses routine_id():

integer bar_ID --bar_ID must be defined before foo()

funcion foo(object x)
    integer z
    z=call_func(bar_ID,{x})
    return z+2
end function

function bar(object y)
    if atom(y) return -1 else return length(y)
end function

bar_ID=routine_id("bar") -- routine_id() must be used after bar()

printf(1,"%d",foo({1,2,3}))


Now this works as foo() can "see" bar_ID and bar_ID is assigned a value
before foo() is called.

-- Mike Nelson