/*
This file is part of LilyPond, the GNU music typesetter.
- Copyright (C) 1999--2011 Han-Wen Nienhuys <hanwen@xs4all.nl>
+ Copyright (C) 1999--2014 Han-Wen Nienhuys <hanwen@xs4all.nl>
LilyPond is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
Simple smobs are created by adding the
DECLARE_SIMPLE_SMOBS(Classname) to the declaration
+ A simple smob is only optionally under the reign of the GUILE
+ garbage collector: its usual life time is that of a normal C++
+ object. While a smobbed_copy () is fully under control of the
+ garbage collector and will have its mark_smob function called during
+ garbage collection, an automatic variable of this type will not have
+ mark_smob called, but rather have its memory image in the call stack
+ scanned for contained non-immediate SCM values. Anything requiring
+ more complex mark_smob behavior is not suitable for a simple smob.
+
+ When you create a smobbed_copy, the _copy_ is fully managed by the
+ GUILE memory system. As a corollary, multiple smobbed_copy calls
+ yield multiple GUILE objects generally not eq? to each other.
+
2. Complex smobs are objects that have an identity. These objects
carry this identity in the form of a self_scm () method, which is a
- SCM pointer to the object itself.
+ SCM pointer to the object itself. Complex smobs are always under
+ control of the GUILE memory system.
The constructor for a complex smob should have 3 steps:
- * initialize all SCM members to a non-immediate value (like SCM_EOL)
+ * initialize all SCM members to an immediate value (like SCM_EOL)
* call smobify_self ()
Complex_smob *p = new Complex_smob;
list = scm_cons (p->self_scm (), list);
- scm_gc_unprotect_object (p->self_scm ());
+ p->unprotect ();
+
+ Since unprotect returns the SCM object itself, this particular case
+ can be written as
+
+ Complex_smob *p = new Complex_smob;
+ list = scm_cons (p->unprotect (), list);
Complex smobs are made with DECLARE_SMOBS (Classname) in the class
declaration.
void unprotect_smob (SCM smob, SCM *prot_cons);
extern bool parsed_objects_should_be_dead;
+class parsed_dead
+{
+ static vector<parsed_dead *> elements;
+ SCM data;
+ SCM readout_one ()
+ {
+ SCM res = data;
+ data = SCM_UNDEFINED;
+ return res;
+ }
+public:
+ parsed_dead () : data (SCM_UNDEFINED)
+ {
+ elements.push_back (this);
+ }
+ void checkin (SCM arg) { data = arg; }
+ static SCM readout ();
+};
#ifndef NDEBUG
-#define ASSERT_LIVE_IS_ALLOWED() \
- do { \
- static bool passed_here_once;\
- if (parsed_objects_should_be_dead && !passed_here_once) { \
- ::programming_error (string ("Parsed object should be dead: ") + __PRETTY_FUNCTION__ ); \
- passed_here_once = true;\
- } \
- } \
- while (0)
+#define ASSERT_LIVE_IS_ALLOWED(arg) \
+ do { \
+ static parsed_dead pass_here; \
+ if (parsed_objects_should_be_dead) \
+ pass_here.checkin (arg); \
+ } while (0)
#else
-#define ASSERT_LIVE_IS_ALLOWED() do { } \
+#define ASSERT_LIVE_IS_ALLOWED(arg) do { (void)(arg); } \
while (0)
#endif