diff options
| -rw-r--r-- | chapel.html.markdown | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/chapel.html.markdown b/chapel.html.markdown index 8b41dc32..77efbf5a 100644 --- a/chapel.html.markdown +++ b/chapel.html.markdown @@ -77,6 +77,15 @@ config param paramCmdLineArg: bool = false; writeln( varCmdLineArg, ", ", constCmdLineArg, ", ", paramCmdLineArg ); // Set config with --set paramCmdLineArg=value at compile time +// refs operate much like a reference in C++ +var actual = 10; +ref refToActual = actual; // refToActual refers to actual +writeln( actual, " == ", refToActual ); // prints the same value +actual = -123; // modify actual (which refToActual refers to) +writeln( actual, " == ", refToActual ); // prints the same value +refToActual = 99999999; // modify what refToActual refers to (which is actual) +writeln( actual, " == ", refToActual ); // prints the same value + // Math operators var a: int, thisInt = 1234, thatInt = 5678; a = thisInt + thatInt; // Addition @@ -426,12 +435,19 @@ intentsProc( inVar, outVar, inoutVar, refVar ); writeln( "Outside After: ", (inVar, outVar, inoutVar, refVar) ); // Similarly we can define intents on the return type -proc makeArray( elems: int, startNumber: int ) ref : [1..#elems] int { - var array: [1..#elems] int; - for idx in array.domain do array[idx] = startNumber + idx; - return array; -} -writeln( makeArray( 10, -1 ) ); +// refElement returns a reference to an element of array +proc refElement( array : [?D] ?T, idx ) ref : T { + return array[ idx ]; // returns a reference to +} + +var myChangingArray : [1..5] int = [1,2,3,4,5]; +writeln( myChangingArray ); +// Store reference to element in ref variable +ref refToElem = refElement( myChangingArray, 5 ); +writeln( refToElem ); +refToElem = -2; // modify reference which modifies actual value in array +writeln( refToElem ); +writeln( myChangingArray ); // This makes more practical sense for class methods where references to // elements in a data-structure are returned via a method or iterator |