Changes between Version 10 and Version 11 of ExpressionTour

Timestamp:

05/31/13 09:24:44 (11 years ago)

Author:

hopscc

Comment:

--

ExpressionTour

@@ -218 +218 @@
 == Nil ==
 
-Operations and literals around nil/null values.[[BR]]
-'''nil''' is the nil/null literal
-
-EXPR to ?
-  - cast the type of EXPR to the nilable form of the same type (EXPR.typeOf?, nilable EXPR.typeof)
-
-EXPR to ! 
-  - cast the type of EXPR to the the non-nilable form of same type( EXPR.typeOf!) 
+Cobra has various operations and literals around nil/null values.[[BR]]
+
+'''nil''' is the nil/null literal.
+
+Cobra provides operators to allow coalescing of expressions that evaluate nil or non nil.[[BR]]
+This saves an explicit nil comparison check and assignment in favor of a coalescing expression or  augmented assignment.
+
+'?' is nil coalesce operator[[BR]]
+'!' is non-nil coalesce operator
 
 EXPR ? EXPR1
@@ -234 +235 @@
 
 EXPR1 ?= EXPR1
-    - nil coalesce EXPR1 to itself or EXPR2
+    - augmented assignment: nil coalesce EXPR1 to itself or EXPR2
     - same as EXPR1 = EXPR1 ? EXPR2
 
 EXPR1 != EXPR1
-    - non-nil coalesce EXPR1 to itself or EXPR2
+    - augmented assignment: non-nil coalesce EXPR1 to itself or EXPR2
     - same as EXPR = EXPR1 ! EXPR2
 
@@ -247 +248 @@
 #!cobra
 
-if a is nil, print 'Bad a'
+if a is nil, print 'Bad a' # explicit comparison and statement
 
 y = a ? b    # coalesce nil : y gets a if a non nil, b otherwise
@@ -264 +265 @@
 }}}
 
+See also wiki:NilableTypes  
 
 == Method References ==