Changes between Version 18 and Version 19 of PIL

Timestamp:

10/16/24 13:17:47 (19 months ago)

Author:

siegel

Comment:

--

PIL

@@ -29 +29 @@
 
 == Types
-- '''type names''' are used for all declarations.  There are no C declarators.  Examples:
+
+=== Basic properties of types
+
+'''type names''' are used for all declarations.  There are no C declarators.  Examples:
  * `$int[] a`: declares `a` to be an array of integer
  * `$int* p`: pointer to integer
@@ -35 +38 @@
  * `$int[]* q`: pointer to array of integer
  * `$int*[]($real) f`: function from Real to array of pointer to integer
-- every type has a default value.  The result of evaluating an erroneous expression is the default value of that type.  (But as explained above, an analyzer may check for all errors.)
+
+Type definitions have the form: `typedef typename ID;`.
+
+Every type has a default value.  The result of evaluating an erroneous expression is the default value of that type.  (But as explained above, an analyzer may check for all errors.)
+
+=== The types
+
 - basic types: 
  * `$bool` : the set consisting of `$true` and `$false`.  Default value: `$false`.
@@ -52 +61 @@
 - `$map<T1,T2>` : finite map from `T1` to `T2`.  A map is a set of ordered pairs `(x,y)` with the property that if `(x,y)` and `(x,z)` are in the map, then `y`=`z`.  Default value: the empty map.
 - `$tuple<T1,...>` : tuples of specified type.  This is similar to `struct`, but there is no tag and the fields do not have names.  Default value: the tuple in which each component has its default value.
-- Type definitions have the form: `typedef typename ID;`
+- `$obj` : the object type.   This is a type for representing a sequence of bytes holding arbitrary values at different intervals.   It is used to model C objects, such as the object created by a call to C's `malloc`.
+
+=== Sized types
+
+The types above are the ''unsized types''  A ''sized type'' comprises an unsized type and a positive integer, which represents the size of the type in bytes.  Syntactically, a sized type is specified
+{{{
+  $size(expr) typename
+}}}
+where expr is an integer constant expression and typename is the name of an unsized type.  For example,
+{{{
+typedef $size(4) $int int;
+typedef $size(8) $int long;
+typedef $size(4) $real float;
+typedef $size(8) $real double;
+}}}
+defines 4 distinct types.  Certain operations require a sized type.
+
 
 == Functions
@@ -289 +314 @@
  * frees the object referred to by `p`, the pointer returned by an earlier call to `$new` or `$alloc`.
 
+== Objects
+
+The following operations are supported on the `$obj` type:
+
+
+
 
 == Questions