Re: [chuck-users] passing by reference

27 Nov 2005


      Hi Eduard and all,
...
I am trying to pass an integer by reference, but I can't get it right. 
Could any one help me on this?  What I tried works fine for arrays, but 
not for integers only.
in chuck, references *cannot* be made to primitive types (int, float, 
dur, time), only to objects.  in function calling, primitives are always 
passed by value, and non-primitives are always passed by reference (like 
in Java), regardless of the usage of @.  However, the compiler should 
have caught the fact that a function has been declared to take an 'int @' 
as argument - this is a bug, which has been fixed now and will be 
included in 1.2.0.4.  Additionally, arrays are always considered objects, 
including arrays of primitives.

as for achieving pass-by-reference for primitive types, one way is to wrap 
them in an object and pass the object:

//----------------------------------------
// slightly modified
// (@ have been removed from func args)
//-----------------------------------------

// define class to wrap int
class TheInt
{
     int value;
}

// instantiate it
TheInt ti;
// set any initial values
5 => ti.value;

// call modify value
ModifyValue( ti, 10 );

// check again
<<< ti.value >>>;

fun void PrintArray( int array[] )
{
     for( 0 => int i ; i < 10; i++ )
         <<<"a[",i,"] = ", array[i]>>>;
}

fun int IsInArray(int array[], int num, int length )
{
    if( length > array.cap() ) array.cap() => length;
    if( !length ) return 0; // array is still empty
    for( 0 => int i; i < length; i++ )
    {
         if( num == array[i] )
         {
             <<>>;
             return 1; // num found in array
         }
    }
    <<< num, " not found in array" >>>;
    return 0; // not found
}

fun void ModifyValue( TheInt val, int newValue )
{
     <<< "val is: " , val.value >>>;
     newValue => val.value;
     <<< "val is: " , val.value >>>;
}

fun void ModifyArray( int array[] )
{
     for(0=>int i; i < array.cap(); i++)
         array[i]*5 => array[i];
}

Re: [chuck-users] passing by reference

Ge Wang