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- Improve the runtime type sytesm

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- Update all languages to new type system
- Add DohSortList function
- Fix mzscheme Examples/Makefile


git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@6930 626c5289-ae23-0410-ae9c-e8d60b6d4f22
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John Lenz 2005-02-01 00:08:24 +00:00
commit f6964f285f
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30
SWIG/Doc/Manual/Guile.html
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@ -388,28 +388,36 @@ If the Scheme object passed was not a SWIG smob representing a compatible
pointer, a <code>wrong-type-arg</code> exception is raised.
<H3><a name="Guile_nn13"></a>18.6.1 GH Smobs</H3>
<p>
In earlier versions of SWIG, C pointers were represented as Scheme
strings containing a hexadecimal rendering of the pointer value and a
mangled type name. As Guile allows registering user types, so-called
"smobs" (small objects), a much cleaner representation has been
implemented now. The details will be discussed in the following.
</p>
<p>
A smob is a cons cell where the lower half of the CAR contains the
smob type tag, while the upper half of the CAR and the whole CDR are
available. <code>SWIG_Guile_Init()</code> registers a smob type named
"swig" with Guile; its type tag is stored in the variable
<code>swig_tag</code>. The upper half of the CAR store an index into
a table of all C pointer types seen so far, to which new types seen
are appended. The CDR stores the pointer value.
<p> A smob is a cons cell where the lower half of the CAR contains the smob type
tag, while the upper half of the CAR and the whole CDR are available. Every
module creates its own smob type in the clientdata field of the module. So the
lower 16 bits of the car of the smob store the tag and the upper 16 bits store
the index this type is in the array. We can then, given a smob, find its
swig_type_info struct by using the tag (lower 16 bits of car) to find which
module this type is in (since each tag is unique for the module). Then we use
the upper 16 bits to index into the array of types attached to this module.
Looking up the module from the tag is worst case O(# of modules) but average
case O(1). This is because the modules are stored in a circularly linked list,
and when we start searching the modules for the tag, we start looking with the
module that the function doing the lookup is in. SWIG_Guile_ConvertPtr() takes
as its first argument the swig_module_info * of the calling function, which is
where we start comparing tags. Most types will be looked up in the same module
that created them, so the first module we check will most likely be correct.
Once we have a swig_type_info structure, we loop through the linked list of
casts, using pointer comparisons.</p>
<H3><a name="Guile_nn14"></a>18.6.2 SCM Smobs</H3>
<p>The SCM interface (using the "-scm" argument to swig) uses common.swg.
<p>The SCM interface (using the "-scm" argument to swig) uses swigrun.swg.
The whole type system, when it is first initialized, creates two smobs named "swig" and "collected_swig".
The swig smob is used for non-garbage collected smobs, while the collected_swig smob is used as described
below. Each smob has the same format, which is a double cell created by SCM_NEWSMOB2()