September Morn Update

Task/Null-object/ARM-Assembly/null-object.arm

@@ -0,0 +1,60 @@
+/* ARM assembly Raspberry PI  */
+/*  program nullobj.s   */
+
+/* Constantes    */
+.equ STDIN,  0                                        @ Linux input console
+.equ STDOUT, 1                                        @ Linux output console
+.equ EXIT,   1                                        @ Linux syscall
+.equ READ,   3                                        @ Linux syscall
+.equ WRITE,  4                                        @ Linux syscall
+
+/* Initialized data */
+.data
+szCarriageReturn:       .asciz "\n"
+szMessResult:           .asciz "Value is null.\n"     @ message result
+
+iPtrObjet:		.int 0                        @ objet pointer
+
+/* UnInitialized data */
+.bss
+
+/*  code section */
+.text
+.global main
+main:                                                @ entry of program
+
+    ldr r0,iAdriPtrObjet                             @ load pointer address
+    ldr r0,[r0]                                      @ load pointer value
+    cmp r0,#0                                        @ is null ?
+    ldreq r0,iAdrszMessResult                        @ yes -> display message
+    bleq affichageMess
+
+
+100:                                                 @ standard end of the program
+    mov r0, #0                                       @ return code
+    pop {fp,lr}                                      @ restaur 2 registers
+    mov r7, #EXIT                                    @ request to exit program
+    svc 0                                            @ perform the system call
+
+iAdrszMessResult:        .int szMessResult
+iAdrszCarriageReturn:    .int szCarriageReturn
+iAdriPtrObjet:           .int iPtrObjet
+/******************************************************************/
+/*     display text with size calculation                         */
+/******************************************************************/
+/* r0 contains the address of the message */
+affichageMess:
+    push {r0,r1,r2,r7,lr}                           @ save  registres
+    mov r2,#0                                       @ counter length
+1:                                                  @ loop length calculation
+    ldrb r1,[r0,r2]                                 @ read octet start position + index
+    cmp r1,#0                                       @ if 0 its over
+    addne r2,r2,#1                                  @ else add 1 in the length
+    bne 1b                                          @ and loop
+                                                    @ so here r2 contains the length of the message
+    mov r1,r0                                       @ address message in r1
+    mov r0,#STDOUT                                  @ code to write to the standard output Linux
+    mov r7, #WRITE                                  @ code call system "write"
+    svc #0                                          @ call systeme
+    pop {r0,r1,r2,r7,lr}                            @ restaur des  2 registres */
+    bx lr                                           @ return

Task/Null-object/Neko/null-object.neko

@@ -0,0 +1,12 @@
+/**
+ <doc>
+ <p>Neko uses <i>null</i> for undefined variables,
+  and also as a programmer accessible value.</p>
+ <p>The <i>null</i> value can be treated as a boolean value with the
+  builtin $istrue, and tests as false.</p>
+ </doc>
+*/
+
+var n = null
+if n == null $print("n is null\n")
+if $not($istrue(n)) $print("and tests as boolean false\n")

Task/Null-object/Nim/null-object.nim

@@ -1,3 +1,4 @@
-var s: string = nil
+let s: pointer = nil
 
-var ns: string not nil = nil # Compile time error
+{.experimental: "notnil".}
+let ns: pointer not nil = nil # Compile time error

Task/Null-object/Swift/null-object-1.swift

@@ -1,2 +1 @@
-var opt : Int? = nil // use "nil" to represent no value
-opt = 5 // or simply assign a value to the optional type
+let maybeInt: Int? = nil

Task/Null-object/Swift/null-object-2.swift

@@ -1,5 +1,5 @@
-if let v = opt {
-    println("There is some value: \(v)")
+if maybeInt == nil {
+  print("variable is nil")
 } else {
-    println("There is no value")
+  print("variable has some value")
 }

Task/Null-object/Swift/null-object-3.swift

@@ -0,0 +1,5 @@
+if let certainlyInt = maybeInt {
+  print("variable has value \(certainlyInt)")
+} else {
+  print("variable is nil")
+}

Task/Null-object/VBA/null-object.vba

@@ -0,0 +1,14 @@
+Public Sub Main()
+    Dim c As VBA.Collection
+
+    ' initial state: Nothing
+    Debug.Print c Is Nothing
+
+    ' create an instance
+    Set c = New VBA.Collection
+    Debug.Print Not c Is Nothing
+
+    ' release the instance
+    Set c = Nothing
+    Debug.Print c Is Nothing
+End Sub