Add all the A tasks

Task/Abstract-type/C/abstract-type-1.c

@@ -0,0 +1,33 @@
+#ifndef INTERFACE_ABS
+#define INTERFACE_ABS
+
+typedef struct sAbstractCls *AbsCls;
+
+typedef struct sAbstractMethods {
+    int         (*method1)(AbsCls c, int a);
+    const char *(*method2)(AbsCls c, int b);
+    void        (*method3)(AbsCls c, double d);
+} *AbstractMethods, sAbsMethods;
+
+struct sAbstractCls {
+    AbstractMethods  klass;
+    void     *instData;
+};
+
+#define ABSTRACT_METHODS( cName, m1, m2, m3 ) \
+    static sAbsMethods cName ## _Iface = { &m1, &m2, &m3 }; \
+    AbsCls cName ## _Instance( void *clInst) { \
+        AbsCls ac = malloc(sizeof(struct sAbstractCls)); \
+        if (ac) { \
+            ac->klass = &cName ## _Iface; \
+            ac->instData = clInst; \
+        }\
+        return ac; }
+
+#define Abs_Method1( c, a) (c)->klass->method1(c, a)
+#define Abs_Method2( c, b) (c)->klass->method2(c, b)
+#define Abs_Method3( c, d) (c)->klass->method3(c, d)
+#define Abs_Free(c) \
+  do { if (c) { free((c)->instData); free(c); } } while(0);
+
+#endif

Task/Abstract-type/C/abstract-type-2.c

@@ -0,0 +1,9 @@
+#ifndef SILLY_H
+#define SILLY_H
+#include intefaceAbs.h
+
+typedef struct sillyStruct *Silly;
+extern Silly NewSilly( double, const char *);
+extern AbsCls Silly_Instance(void *);
+
+#endif

Task/Abstract-type/C/abstract-type-3.c

@@ -0,0 +1,42 @@
+#include "silly.h"
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+struct sillyStruct {
+    double  v1;
+    char   str[32];
+};
+
+Silly NewSilly(double vInit, const char *strInit)
+{
+    Silly sily = malloc(sizeof( struct sillyStruct ));
+    sily->v1 = vInit;
+    sily->str[0] = '\0';
+    strncat(sily->str, strInit, 31);
+    return sily;
+}
+
+static
+int MyMethod1(  AbsCls c, int a)
+{
+    Silly s = (Silly)(c->instData);
+    return a+strlen(s->str);
+}
+
+static
+const char *MyMethod2(AbsCls c, int b)
+{
+    Silly s = (Silly)(c->instData);
+    sprintf(s->str, "%d", b);
+    return s->str;
+}
+
+static
+void  MyMethod3(AbsCls c, double d)
+{
+    Silly s = (Silly)(c->instData);
+    printf("InMyMethod3, %f\n",s->v1 * d);
+}
+
+ABSTRACT_METHODS( Silly, MyMethod1, MyMethod2, MyMethod3)

Task/Abstract-type/C/abstract-type-4.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include "silly.h"
+
+int main()
+{
+    AbsCls abster = Silly_Instance(NewSilly( 10.1, "Green Tomato"));
+
+    printf("AbsMethod1: %d\n", Abs_Method1(abster, 5));
+    printf("AbsMethod2: %s\n", Abs_Method2(abster, 4));
+    Abs_Method3(abster, 21.55);
+    Abs_Free(abster);
+    return 0;
+}