Changes between Version 22 and Version 23 of PIL

Timestamp:

10/16/24 20:18:45 (19 months ago)

Author:

siegel

Comment:

--

PIL

@@ -71 +71 @@
 where expr is an integer constant expression and typename is the name of an unsized type.  For example,
 {{{
+typedef $size(1) $int char;
 typedef $size(4) $int int;
 typedef $size(8) $int long;
@@ -76 +77 @@
 typedef $size(8) $real double;
 }}}
-defines 4 distinct types.  Certain operations require a sized type.
+defines 5 distinct types.  Certain operations require a sized type.
+
+Restrictions on sized types:
+ - an array type cannot be sized
+ - the type `$obj` cannot be sized
+ - if a struct type is sized and all of its fields have sized types then the size of the struct
+   must be the sum of the sizes of the fields
+ - if a union type is sized then the size of the union must be greater than or equal to the
+   size of any sized type field
+
+Note on translation from C: C structs can have "padding" after each field.  This can be modeled
+in PIL by making the padding explicit, e.g.,
+{{{
+struct Pair {
+  int i;
+  char[2] _padding1;
+  double x;
+  char[4] _padding2;
+}}}
+
+Except... you can do things like `char[2]` in PIL, hmmm, have to think about this.