SparrowOSTS_121127.ISO

SparrowOS/Demo/ClassMeta.CPP

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+//This demonstrates class meta data.
+//Basically, we make use of the compiler's
+//data about a class.  We can add to the
+//compilers data arbitrary items, either string or
+//or int or F64 (if you typecast).
+
+//This stuff is not high performance.
+//Don't get carried away -- it might be slow.
+
+
+U0 RankOut(I64 i)
+{
+  " %z",i,"Cadet\0Ensign\0Captain\0Admiral\0President\0";
+}
+
+class Test1Struct
+{
+  I64 age	printf_str "%2d" dft_val 38;
+  I64 color	dft_val RED; //Accepts expressions
+  I64 rank	printf_str "%1d" dft_val 6/2 output_fun &RankOut;
+};
+
+class Test2Struct
+{
+  I64 age	 printf_str "%2d" dft_val 38 percentile 54.20;
+  I64 rank	 printf_str "%1d" dft_val 5;
+  I64 serial_num printf_str "%6d" dft_val 123456;
+};
+
+
+U0 DumpStruct(U8 *class_name,U8 *data)
+{
+  CHashClass *tempc=HashFind(class_name,Fs->hash_table,HTT_CLASS);
+  U8 *printf_str;
+  I64 *q,dft_val;
+  U0 (* fp_output_fun)(I64 i);
+  F64 percentile;
+  if (!tempc) return;
+  CMemberList *ml;
+  ml=tempc->member_list;
+  while (ml) {
+    "%s:",ml->str;
+
+//All our items are I64's.  If you want, you can check
+//the data type of the member var.  See $LK,"ClassRep","MN:ClassRep"$().
+    q=data+ml->offset;
+
+    if (printf_str=MemberMetaData("printf_str",ml))
+      "" printf_str,*q;
+
+//This is slightly ambiguous -- if no meta is present it will return zero.
+    if (dft_val=MemberMetaData("dft_val",ml))
+      " default:%d",dft_val;
+
+//This corrects for the ambiguity, allowing zero percentile.
+    if (MemberMetaFind("percentile",ml)) { //check if it exists
+//We could use the $LK,"CMemberListMeta","MN:CMemberListMeta"$ structure returned by
+//$LK,"MemberMetaFind","MN:MemberMetaFind"$() and save a search.
+      percentile=MemberMetaData("percentile",ml)(F64);
+      " percentile: %5.2f",percentile;
+    }
+
+    if (fp_output_fun=MemberMetaData("output_fun",ml))
+      (*fp_output_fun)(*q);
+    NewLine;
+    ml=ml->next;
+  }
+}
+
+Test1Struct t1;
+t1.age=44;
+t1.rank=3;
+
+DumpStruct("Test1Struct",&t1);
+
+Test2Struct t2;
+t2.age=22;
+t2.rank=2;
+t2.serial_num=55555;
+
+DumpStruct("Test2Struct",&t2);