[Nice-commit] Nice/stdlib/nice/lang prelude.nice,1.40,1.41

[Artem Gr K. <ar...@us...>]

Update of /cvsroot/nice/Nice/stdlib/nice/lang
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv9419/stdlib/nice/lang

Modified Files:
	prelude.nice 
Log Message:
maybeNull

Index: prelude.nice
===================================================================
RCS file: /cvsroot/nice/Nice/stdlib/nice/lang/prelude.nice,v
retrieving revision 1.40
retrieving revision 1.41
diff -C2 -d -r1.40 -r1.41
*** prelude.nice	5 Nov 2004 15:22:05 -0000	1.40
--- prelude.nice	7 Mar 2005 09:49:21 -0000	1.41
***************
*** 38,48 ****
  final class Null<+T> extends Maybe<T> = native;
  
! /** 
!     Throws java.lang.NullPointerException if the argument is <code>null</code>.
! 
!     This call presently does no check, assuming that a dereferencing
!     is coming next and will detect nullness.
!     This should probably be fixed so that the semantics is well defined.
! */
  <T> !T notNull(?T value)
  {
--- 38,45 ----
  final class Null<+T> extends Maybe<T> = native;
  
! /**
!  * Assert that a <code>value</code> it not <code>null</code>.
!  * Throws java.lang.AssertionError if assertions are enabled and the argument is <code>null</code>.
!  */
  <T> !T notNull(?T value)
  {
***************
*** 51,54 ****
--- 48,63 ----
  }
  
+ /**
+  * Tell the compiler that the <code>value</code> might be <code>null</code>.<br>
+  * Useful to check if the variable is <code>null</code>
+  * without issuing a compile-time warning: <code>if( maybeNull( var ) == null )</code>.<br>
+  * The need for this method might arise in particular when using
+  * existing Java libraries. Nice often thinks that Java method
+  * would not return a <code>null</code> value, and it is not always practical
+  * to write a retyping for the method.<br>
+  * See also the "Option types" chapter of the Nice manual.
+  */
+ <T> ?T maybeNull(!T value) = value;
+ 
  /****************************************************************
   * Primitive types