Merge lp:~smspillaz/compiz-libcompizconfig/refactor-context into lp:~compiz-team/compiz-libcompizconfig/0.9.8

[Sam Spilsbury]

This is all about bug 990690.

!! - It probably isn't a good idea to test this branch in isolation, as it is part of a pipeline to get compiz-libcompizconfig under test. If you want to test the result of this work, you should probably look at testing

lp:~smspillaz/compiz-libcompizconfig/setting-mock
lp:~smspillaz/compiz-compizconfig-python/compiz-compizconfig-python.setting-api
lp:~smspillaz/compiz-compizconfig-gconf/compiz-compizconfig-gconf.adapt-to-new-interfaces

.. that's all !!

Refactors CCSContext to indirect all variables behind a private ptr

[Alan Griffiths (alan-griffiths)]

There's not much point to a structure that only contains a void pointer.

The pattern I'd expect is:

// *.h
typedef struct CCSContext CCSContext;
CCSContext* ccsContextCreate();
CCSPluginList ccsContextGetPlugins(CCSContext*);
...
void ccsContextDestroy(CCSContext*);

// *.cpp
struct CCSContext
{
    CCSBackend *backend;
    CCSPluginList plugins; /* list of plugins settings were loaded for */
    CCSPluginCategory *categories; /* list of plugin categories */
    void *privatePtr; /* private pointer that can be used by the caller */
    char *profile;
    Bool deIntegration;
    Bool pluginListAutoSort;

    unsigned int configWatchId;

    CCSSettingList changedSettings; /* list of settings changed since last settings write */

    unsigned int screenNum; /* screen number this context is assigned to */
    const CCSInterfaceTable *object_interfaces;
    const CCSContextInterface *interface;
} CCSContextPrivate;
...
CCSPluginList
ccsContextGetPluginsDefault (CCSContext* context)
{
  return context->plugins;
}
...

Maybe there is a reason for the extra complexity? But it escapes me.

review: Needs Fixing

[Alan Griffiths (alan-griffiths)]

> There's not much point to a structure that only contains a void pointer.
>
> The pattern I'd expect is:
>
> // *.h
> typedef struct CCSContext CCSContext;
> CCSContext* ccsContextCreate();
> CCSPluginList ccsContextGetPlugins(CCSContext*);
> ...
> void ccsContextDestroy(CCSContext*);
>
> // *.cpp
> struct CCSContext
> {
> CCSBackend *backend;
> CCSPluginList plugins; /* list of plugins settings were loaded for */
> CCSPluginCategory *categories; /* list of plugin categories */
> void *privatePtr; /* private pointer that can be used by the caller */
> char *profile;
> Bool deIntegration;
> Bool pluginListAutoSort;
>
> unsigned int configWatchId;
>
> CCSSettingList changedSettings; /* list of settings changed since last
> settings write */
>
> unsigned int screenNum; /* screen number this context is assigned to */
> const CCSInterfaceTable *object_interfaces;
> const CCSContextInterface *interface;
> } CCSContextPrivate;

Cut&past error - that should be "> };"

> ...
> CCSPluginList
> ccsContextGetPluginsDefault (CCSContext* context)
> {
> return context->plugins;
> }
> ...
>
> Maybe there is a reason for the extra complexity? But it escapes me.

[Sam Spilsbury (smspillaz)]

Agreed, changing to opaque pointers was something I didn't remember to do yet. doing it now.

[Sam Spilsbury (smspillaz)]

> There's not much point to a structure that only contains a void pointer.
>
> The pattern I'd expect is:
>
> // *.h
> typedef struct CCSContext CCSContext;
> CCSContext* ccsContextCreate();
> CCSPluginList ccsContextGetPlugins(CCSContext*);
> ...
> void ccsContextDestroy(CCSContext*);
>
> // *.cpp
> struct CCSContext
> {
> CCSBackend *backend;
> CCSPluginList plugins; /* list of plugins settings were loaded for */
> CCSPluginCategory *categories; /* list of plugin categories */
> void *privatePtr; /* private pointer that can be used by the caller */
> char *profile;
> Bool deIntegration;
> Bool pluginListAutoSort;
>
> unsigned int configWatchId;
>
> CCSSettingList changedSettings; /* list of settings changed since last
> settings write */
>
> unsigned int screenNum; /* screen number this context is assigned to */
> const CCSInterfaceTable *object_interfaces;
> const CCSContextInterface *interface;
> } CCSContextPrivate;
> ...
> CCSPluginList
> ccsContextGetPluginsDefault (CCSContext* context)
> {
> return context->plugins;
> }
> ...
>
> Maybe there is a reason for the extra complexity? But it escapes me.

See the next pipe - it contains a struct that contains a CCSObject (not by pointer). All this does is move the data behind an indirection pimpl.

[Sam Spilsbury (smspillaz)]

A clarification - the way CCSObject works means that "object types" in libcompizconfig can't be behind opaque pointers is because at the moment we are just doing allocation manually (eg no fooNew ... yet as its nontrivial with the current design). In order to ensure that we get enough allocated for CCSObject and can access it easily from any object type is to make it the first member of the struct and then hide everything behind the priv pointer it provides.

[Alan Griffiths (alan-griffiths)]

I can think of no good reason that ccsPrivate is void* instead of CCSContextPrivate* - that would allow the implementation code to be simpler by removing the need for casts.

And I don't see why CONTEXT_PRIV and _CCSContextPrivate/CCSContextPrivate are defined in a header.

Which is "the next pipe"?

[Sam Spilsbury (smspillaz)]

Each of these branches is part of a pipeline (eg, changes are made in serial and each is dependent on the last). This can be traversed backwards from setting-mock.

At the moment, the pattern I'm using here is

1) Move private data behind a pimpl and use accessor methods to get at the data
2) Create an interface structure and make all method calls for that object go through that interface structure.

Hence the reason why ccsPrivate is void * (for the time being).

[Sam Spilsbury (smspillaz)]

CONTEXT_PRIV and related things are defined in headers because they are used in multiple source files. This will be changed eventually, but in another branch (for the sake of /not/ rewriting libcompizconfig in one MP)

[Alan Griffiths (alan-griffiths)]

> CONTEXT_PRIV and related things are defined in headers because they are used
> in multiple source files. This will be changed eventually, but in another
> branch (for the sake of /not/ rewriting libcompizconfig in one MP)

AFAICS CONTEXT_PRIV, _CCSContextPrivate and CCSContextPrivate are only used in main.c (but that isn't the real point).

[Alan Griffiths (alan-griffiths)]

I'm still struggling to identify the design goals here.

Indirecting calls via a CCSContextInterface member pointer gives the capability to change the implementation of individual functions on an instance by instance basis. Is this needed? Or just a seam for testing? If the latter, then there's no need for objects to carry around a pointer.

I also don't see what the additional indirection through CCSInterfaceTable* is for. The only use is ccsEmptyContextNew which assigns to object_interfaces, but where is it used? And what for?

[Sam Spilsbury (smspillaz)]

On Fri, 4 May 2012, Alan Griffiths wrote:

> I'm still struggling to identify the design goals here.
>
> Indirecting calls via a CCSContextInterface member pointer gives the capability to change the implementation of individual functions on an instance by instance basis. Is this needed? Or just a seam for testing? If the latter, then there's no need for objects to carry around a pointer.
>

Sure, it is a seam for testing. However, its useful in that we can test by
having a real CCSPlugin, CCSContext and a mocked CCSSetting or vice-versa.
We may also want to test interactiosn between individual setting objects
themselves vis-a-vis keybinding conflicts.

> I also don't see what the additional indirection through CCSInterfaceTable* is for. The only use is ccsEmptyContextNew which assigns to object_interfaces, but where is it used? And what for?
>

At the moment, this is so that you can override the kind of objet that
might be constructed by a CCSContexted or CCSPlugin internally. This will
be replaced when the code is further refactored to truly do dependency
injection.

>
> --
> https://code.launchpad.net/~smspillaz/compiz-libcompizconfig/refactor-context/+merge/104469
> You are the owner of lp:~smspillaz/compiz-libcompizconfig/refactor-context.
>

[lp:~smspillaz/compiz-libcompizconfig/refactor-context]

437. By Sam Spilsbury on 2012-05-04

Merged ccs-object into refactor-context.

438. By Sam Spilsbury on 2012-05-04

Merged ccs-object into refactor-context.

439. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

440. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

441. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

442. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

Unmerged revisions

442. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

441. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

440. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

439. By Sam Spilsbury on 2012-05-07

Merged ccs-object into refactor-context.

438. By Sam Spilsbury on 2012-05-04

Merged ccs-object into refactor-context.

437. By Sam Spilsbury on 2012-05-04

Merged ccs-object into refactor-context.

436. By Sam Spilsbury on 2012-05-02

Merged ccs-object into refactor-context.

435. By Sam Spilsbury on 2012-04-28

Merged ccs-object into refactor-context.

434. By Sam Spilsbury on 2012-04-28

Merged ccs-object into refactor-context.

433. By Sam Spilsbury on 2012-04-28

Merged ccs-object into refactor-context.

=== modified file 'backend/src/ini.c'
--- backend/src/ini.c	2011-08-20 19:03:37 +0000
+++ backend/src/ini.c	2012-05-04 19:29:21 +0000
@@ -265,7 +265,7 @@
     if (!data)
 	return;
 
-    asprintf (&keyName, "s%d_%s", context->screenNum, setting->name);
+    asprintf (&keyName, "s%d_%s", ccsContextGetScreenNum (context), setting->name);
 
     switch (setting->type)
     {
@@ -455,7 +455,7 @@
     if (!data)
 	return;
 
-    asprintf (&keyName, "s%d_%s", context->screenNum, setting->name);
+    asprintf (&keyName, "s%d_%s", ccsContextGetScreenNum (context), setting->name);
 
     if (setting->isDefault)
     {

=== modified file 'include/ccs.h'
--- include/ccs.h	2012-05-04 19:29:21 +0000
+++ include/ccs.h	2012-05-04 19:29:21 +0000
@@ -247,20 +247,60 @@
 CCSREF_HDR (StrRestriction, CCSStrRestriction)
 CCSREF_HDR (StrExtension, CCSStrExtension)
 
+typedef struct _CCSInterfaceTable CCSInterfaceTable;
+typedef struct _CCSContextInterface CCSContextInterface;
+
+struct _CCSInterfaceTable
+{
+    const CCSContextInterface *contextInterface;
+};
+
+extern const CCSInterfaceTable ccsDefaultInterfaceTable;
+
+/* CCSContext interface */
+typedef CCSPluginList (*CCSContextGetPluginsProc) (CCSContext *context);
+typedef CCSPluginCategory * (*CCSContextGetCategories) (CCSContext *context);
+typedef CCSSettingList (*CCSContextGetChangedSettings) (CCSContext *context);
+typedef unsigned int (*CCSContextGetScreenNum) (CCSContext *context);
+typedef Bool (*CCSContextAddChangedSetting) (CCSContext *context, CCSSetting *setting);
+typedef Bool (*CCSContextClearChangedSettings) (CCSContext *context);
+typedef CCSSettingList (*CCSContextStealChangedSettings) (CCSContext *context);
+typedef void * (*CCSContextGetPrivatePtr) (CCSContext *context);
+typedef void (*CCSContextSetPrivatePtr) (CCSContext *context, void *ptr);
+
+struct _CCSContextInterface
+{
+    CCSContextGetPluginsProc contextGetPlugins;
+    CCSContextGetCategories contextGetCategories;
+    CCSContextGetChangedSettings contextGetChangedSettings;
+    CCSContextGetScreenNum contextGetScreenNum;
+    CCSContextAddChangedSetting contextAddChangedSetting;
+    CCSContextClearChangedSettings contextClearChangedSettings;
+    CCSContextStealChangedSettings contextStealChangedSettings;
+    CCSContextGetPrivatePtr contextGetPrivatePtr;
+    CCSContextSetPrivatePtr contextSetPrivatePtr;
+};
+
+/* CCSContext accessor functions */
+CCSPluginList ccsContextGetPlugins (CCSContext *);
+CCSPluginCategory * ccsContextGetCategories (CCSContext *);
+CCSSettingList ccsContextGetChangedSettings (CCSContext *);
+unsigned int ccsContextGetScreenNum (CCSContext *);
+Bool ccsContextAddChangedSetting (CCSContext *context, CCSSetting *setting);
+Bool ccsContextClearChangedSettings (CCSContext *context);
+CCSSettingList ccsContextStealChangedSettings (CCSContext *context);
+void * ccsContextGetPrivatePtr (CCSContext *context);
+void ccsContextSetPrivatePtr (CCSContext *context, void *ptr);
+
+/* only for bindings */
+void * ccsContextGetPluginsBindable (CCSContext *context);
+void * ccsContextStealChangedSettingsBindable (CCSContext *context);
+void * ccsContextGetChangedSettingsBindable (CCSContext *context);
+
 struct _CCSContext
 {
-    CCSPluginList     plugins;         /* list of plugins settings
-					  were loaded for */
-    CCSPluginCategory *categories;     /* list of plugin categories */
-    void              *privatePtr;     /* private pointer that can be used
-					  by the caller */
     void              *ccsPrivate;     /* private pointer for compizconfig
 					  internal usage */
-
-    CCSSettingList    changedSettings; /* list of settings changed since last
-					  settings write */
-
-    unsigned int screenNum; /* screen number this context is assigned to */
 };
 
 struct _CCSBackendInfo
@@ -534,11 +574,11 @@
 
 /* Creates a new context for the given screen.
    All plugin settings are automatically enumerated. */
-CCSContext* ccsContextNew (unsigned int screenNum);
+CCSContext* ccsContextNew (unsigned int screenNum, const CCSInterfaceTable *);
 
 /* Creates a new context without auto-enumerating any plugin or setting.
    Behaves otherwise exactly like ccsContextNew. */
-CCSContext* ccsEmptyContextNew (unsigned int screenNum);
+CCSContext* ccsEmptyContextNew (unsigned int screenNum, const CCSInterfaceTable *);
 
 /* Destroys the allocated context. */
 void ccsContextDestroy (CCSContext * context);

=== modified file 'plugin/ccp/src/ccp.cpp'
--- plugin/ccp/src/ccp.cpp	2011-08-20 19:03:37 +0000
+++ plugin/ccp/src/ccp.cpp	2012-05-04 19:29:21 +0000
@@ -429,15 +429,14 @@
 
     ccsProcessEvents (mContext, flags);
 
-    if (ccsSettingListLength (mContext->changedSettings))
+    CCSSettingList list = ccsContextStealChangedSettings (mContext);
+
+    if (ccsSettingListLength (list))
     {
-	CCSSettingList list = mContext->changedSettings;
 	CCSSettingList l = list;	
 	CCSSetting     *s;
     	CompPlugin     *p;
     	CompOption     *o;
-
-	mContext->changedSettings = NULL;
 	
 	while (l)
 	{
@@ -456,8 +455,7 @@
 	}
 
 	ccsSettingListFree (list, FALSE);
-	mContext->changedSettings =
-	    ccsSettingListFree (mContext->changedSettings, FALSE);
+	ccsContextClearChangedSettings (mContext);
     }
 
     return true;
@@ -513,11 +511,10 @@
 {
     ccsSetBasicMetadata (TRUE);
 
-    mContext = ccsContextNew (screen->screenNum ());
+    mContext = ccsContextNew (screen->screenNum (), &ccsDefaultInterfaceTable);
     ccsReadSettings (mContext);
 
-    mContext->changedSettings =
-	ccsSettingListFree (mContext->changedSettings, FALSE);
+    ccsContextClearChangedSettings (mContext);
 
     mReloadTimer.start (boost::bind (&CcpScreen::reload, this), 0);
     mTimeoutTimer.start (boost::bind (&CcpScreen::timeout, this),

=== modified file 'src/ccs-private.h'
--- src/ccs-private.h	2011-08-20 19:03:37 +0000
+++ src/ccs-private.h	2012-05-04 19:29:21 +0000
@@ -35,12 +35,23 @@
 typedef struct _CCSContextPrivate
 {
     CCSBackend        *backend;
-
+    CCSPluginList     plugins;         /* list of plugins settings
+                                          were loaded for */
+    CCSPluginCategory *categories;     /* list of plugin categories */
+    void              *privatePtr;     /* private pointer that can be used
+					  by the caller */
     char              *profile;
     Bool	      deIntegration;
     Bool              pluginListAutoSort;
 
     unsigned int      configWatchId;
+
+    CCSSettingList    changedSettings; /* list of settings changed since last
+                                          settings write */
+
+    unsigned int screenNum; /* screen number this context is assigned to */
+    const CCSInterfaceTable *object_interfaces;
+    const CCSContextInterface *interface;
 } CCSContextPrivate;
 
 typedef struct _CCSPluginPrivate

=== modified file 'src/compiz.cpp'
--- src/compiz.cpp	2012-01-23 11:37:14 +0000
+++ src/compiz.cpp	2012-05-04 19:29:21 +0000
@@ -845,6 +845,8 @@
     CCSPlugin *plugin;
     CCSPluginPrivate *pPrivate;
 
+    CONTEXT_PRIV (context);
+
     name = pluginInfoPB.name ().c_str ();
 
     if (!strlen (name))
@@ -908,7 +910,7 @@
 
     initRulesFromPB (plugin, pluginInfoPB);
 
-    context->plugins = ccsPluginListAppend (context->plugins, plugin);
+    cPrivate->plugins = ccsPluginListAppend (cPrivate->plugins, plugin);
 }
 
 static void
@@ -923,6 +925,8 @@
     if (ccsFindPlugin (context, "core"))
 	return;
 
+    CONTEXT_PRIV (context);
+
     plugin = (CCSPlugin*) calloc (1, sizeof (CCSPlugin));
     if (!plugin)
 	return;
@@ -970,7 +974,7 @@
     }
 
     initRulesFromPB (plugin, pluginInfoPB);
-    context->plugins = ccsPluginListAppend (context->plugins, plugin);
+    cPrivate->plugins = ccsPluginListAppend (cPrivate->plugins, plugin);
 }
 
 #endif
@@ -2471,6 +2475,8 @@
     CCSPlugin *plugin;
     CCSPluginPrivate *pPrivate;
 
+    CONTEXT_PRIV (context);
+
     if (!node)
 	return FALSE;
 
@@ -2539,7 +2545,7 @@
 
     initRulesFromRootNode (plugin, node, pluginInfoPBv);
 
-    context->plugins = ccsPluginListAppend (context->plugins, plugin);
+    cPrivate->plugins = ccsPluginListAppend (cPrivate->plugins, plugin);
     free (name);
 
     return TRUE;
@@ -2555,6 +2561,8 @@
     CCSPlugin *plugin;
     CCSPluginPrivate *pPrivate;
 
+    CONTEXT_PRIV (context);
+
     if (!node)
 	return FALSE;
 
@@ -2603,7 +2611,7 @@
 #endif
 
     initRulesFromRootNode (plugin, node, pluginInfoPBv);
-    context->plugins = ccsPluginListAppend (context->plugins, plugin);
+    cPrivate->plugins = ccsPluginListAppend (cPrivate->plugins, plugin);
 
     return TRUE;
 }
@@ -2899,6 +2907,8 @@
     CCSPlugin *plugin;
     CCSPluginPrivate *pPrivate;
 
+    CONTEXT_PRIV (context);
+
     if (ccsFindPlugin (context, name))
 	return;
 
@@ -2933,7 +2943,7 @@
 
     pPrivate->loaded = TRUE;
     collateGroups (pPrivate);
-    context->plugins = ccsPluginListAppend (context->plugins, plugin);
+    cPrivate->plugins = ccsPluginListAppend (cPrivate->plugins, plugin);
 }
 
 static void

=== modified file 'src/main.c'
--- src/main.c	2012-05-04 19:29:21 +0000
+++ src/main.c	2012-05-04 19:29:21 +0000
@@ -260,7 +260,7 @@
 }
 
 CCSContext *
-ccsEmptyContextNew (unsigned int screenNum)
+ccsEmptyContextNew (unsigned int screenNum, const CCSInterfaceTable *object_interfaces)
 {
     CCSContext *context;
 
@@ -277,7 +277,9 @@
 
     CONTEXT_PRIV (context);
 
-    context->screenNum = screenNum;
+    cPrivate->object_interfaces = object_interfaces;
+    cPrivate->interface = object_interfaces->contextInterface;
+    cPrivate->screenNum = screenNum;
 
     initGeneralOptions (context);
     cPrivate->configWatchId = ccsAddConfigWatch (context, configChangeNotify);
@@ -292,13 +294,198 @@
     return context;
 }
 
+static void *
+ccsContextGetPrivatePtrDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return cPrivate->privatePtr;
+}
+
+static void
+ccsContextSetPrivatePtrDefault (CCSContext *context, void *ptr)
+{
+    CONTEXT_PRIV (context);
+
+    cPrivate->privatePtr = ptr;
+}
+
+static CCSPluginList
+ccsContextGetPluginsDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return cPrivate->plugins;
+}
+
+static CCSPluginCategory *
+ccsContextGetCategoriesDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return cPrivate->categories;
+}
+
+static CCSSettingList
+ccsContextGetChangedSettingsDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return cPrivate->changedSettings;
+}
+
+static unsigned int
+ccsContextGetScreenNumDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return cPrivate->screenNum;
+}
+
+static Bool
+ccsContextAddChangedSettingDefault (CCSContext *context, CCSSetting *setting)
+{
+    CONTEXT_PRIV (context);
+
+    cPrivate->changedSettings = ccsSettingListAppend (cPrivate->changedSettings, setting);
+
+    return TRUE;
+}
+
+static Bool
+ccsContextClearChangedSettingsDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    cPrivate->changedSettings = ccsSettingListFree (cPrivate->changedSettings, FALSE);
+
+    return TRUE;
+}
+
+static CCSSettingList
+ccsContextStealChangedSettingsDefault (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    CCSSettingList l = cPrivate->changedSettings;
+
+    cPrivate->changedSettings = NULL;
+    return l;
+}
+
+static const CCSContextInterface ccsDefaultContextInterface =
+{
+    ccsContextGetPluginsDefault,
+    ccsContextGetCategoriesDefault,
+    ccsContextGetChangedSettingsDefault,
+    ccsContextGetScreenNumDefault,
+    ccsContextAddChangedSettingDefault,
+    ccsContextClearChangedSettingsDefault,
+    ccsContextStealChangedSettingsDefault,
+    ccsContextGetPrivatePtrDefault,
+    ccsContextSetPrivatePtrDefault
+};
+
+CCSPluginList
+ccsContextGetPlugins (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextGetPlugins) (context);
+}
+
+CCSPluginCategory *
+ccsContextGetCategories (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextGetCategories) (context);
+}
+
+CCSSettingList
+ccsContextGetChangedSettings (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextGetChangedSettings) (context);
+}
+
+unsigned int
+ccsContextGetScreenNum (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextGetScreenNum) (context);
+}
+
+Bool
+ccsContextAddChangedSetting (CCSContext *context, CCSSetting *setting)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextAddChangedSetting) (context, setting);
+}
+
+Bool
+ccsContextClearChangedSettings (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextClearChangedSettings) (context);
+}
+
+CCSSettingList
+ccsContextStealChangedSettings (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextStealChangedSettings) (context);
+}
+
+void *
+ccsContextGetPrivatePtr (CCSContext *context)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextGetPrivatePtr) (context);
+}
+
+void
+ccsContextSetPrivatePtr (CCSContext *context, void *ptr)
+{
+    CONTEXT_PRIV (context);
+
+    return (*cPrivate->interface->contextSetPrivatePtr) (context, ptr);
+}
+
+void *
+ccsContextGetPluginsBindable (CCSContext *context)
+{
+    return (void *) ccsContextGetPlugins (context);
+}
+
+void *
+ccsContextStealChangedSettingsBindable (CCSContext *context)
+{
+    return (void *) ccsContextStealChangedSettings (context);
+}
+
+void *
+ccsContextGetChangedSettingsBindable (CCSContext *context)
+{
+    return (void *) ccsContextGetChangedSettings (context);
+}
+
+
 static void
 ccsSetActivePluginList (CCSContext * context, CCSStringList list)
 {
     CCSPluginList l;
     CCSPlugin     *plugin;
 
-    for (l = context->plugins; l; l = l->next)
+    CONTEXT_PRIV (context);
+
+    for (l = cPrivate->plugins; l; l = l->next)
     {
 	PLUGIN_PRIV (l->data);
 	pPrivate->active = FALSE;
@@ -325,10 +512,10 @@
 }
 
 CCSContext *
-ccsContextNew (unsigned int screenNum)
+ccsContextNew (unsigned int screenNum, const CCSInterfaceTable *iface)
 {
     CCSPlugin  *p;
-    CCSContext *context = ccsEmptyContextNew (screenNum);
+    CCSContext *context = ccsEmptyContextNew (screenNum, iface);
     if (!context)
 	return NULL;
 
@@ -367,7 +554,9 @@
     if (!name)
 	name = "";
 
-    CCSPluginList l = context->plugins;
+    CONTEXT_PRIV (context);
+
+    CCSPluginList l = cPrivate->plugins;
     while (l)
     {
 	if (!strcmp (l->data->name, name))
@@ -502,14 +691,14 @@
     if (cPrivate->configWatchId)
 	ccsRemoveFileWatch (cPrivate->configWatchId);
 
-    if (c->changedSettings)
-	ccsSettingListFree (c->changedSettings, FALSE);
+    if (cPrivate->changedSettings)
+	cPrivate->changedSettings = ccsSettingListFree (cPrivate->changedSettings, FALSE);
+
+    ccsPluginListFree (cPrivate->plugins, TRUE);
 
     if (c->ccsPrivate)
 	free (c->ccsPrivate);
 
-    ccsPluginListFree (c->plugins, TRUE);
-
     free (c);
 }
 
@@ -1135,9 +1324,7 @@
 	ccsFreeSettingValue (setting->value);
 
 	if (processChanged)
-	    setting->parent->context->changedSettings =
-		ccsSettingListAppend (setting->parent->context->changedSettings,
-				       setting);
+	    ccsContextAddChangedSetting (setting->parent->context, setting);
     }
 
     setting->value = &setting->defaultValue;
@@ -1227,9 +1414,7 @@
     setting->value->value.asInt = data;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1264,9 +1449,7 @@
     setting->value->value.asFloat = data;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1300,9 +1483,7 @@
     setting->value->value.asBool = data;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1338,9 +1519,7 @@
     setting->value->value.asString = strdup (data);
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-		ccsSettingListAppend (setting->parent->context->changedSettings,
-				      setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1373,9 +1552,7 @@
     setting->value->value.asColor = data;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1411,9 +1588,7 @@
     setting->value->value.asMatch = strdup (data);
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1447,9 +1622,7 @@
     setting->value->value.asKey.keyModMask = data.keyModMask;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1484,9 +1657,7 @@
     setting->value->value.asButton.edgeMask = data.edgeMask;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1517,9 +1688,7 @@
     setting->value->value.asEdge = data;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	     ccsSettingListAppend (setting->parent->context->changedSettings,
-				   setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1550,9 +1719,7 @@
     setting->value->value.asBell = data;
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1672,9 +1839,7 @@
     }
 
     if (processChanged)
-	setting->parent->context->changedSettings =
-	    ccsSettingListAppend (setting->parent->context->changedSettings,
-				  setting);
+	ccsContextAddChangedSetting (setting->parent->context, setting);
 
     return TRUE;
 }
@@ -1857,8 +2022,10 @@
 CCSPluginList
 ccsGetActivePluginList (CCSContext * context)
 {
+    CONTEXT_PRIV (context);
+
     CCSPluginList rv = NULL;
-    CCSPluginList l = context->plugins;
+    CCSPluginList l = cPrivate->plugins;
 
     while (l)
     {
@@ -2222,7 +2389,7 @@
 	if (!(*cPrivate->backend->vTable->readInit) (context))
 	    return;
 
-    CCSPluginList pl = context->plugins;
+    CCSPluginList pl = cPrivate->plugins;
     while (pl)
     {
 	PLUGIN_PRIV (pl->data);
@@ -2290,7 +2457,7 @@
 	if (!(*cPrivate->backend->vTable->writeInit) (context))
 	    return;
 
-    CCSPluginList pl = context->plugins;
+    CCSPluginList pl = cPrivate->plugins;
     while (pl)
     {
 	PLUGIN_PRIV (pl->data);
@@ -2308,8 +2475,8 @@
     if (cPrivate->backend->vTable->writeDone)
 	(*cPrivate->backend->vTable->writeDone) (context);
 
-    context->changedSettings =
-	ccsSettingListFree (context->changedSettings, FALSE);
+    cPrivate->changedSettings =
+	ccsSettingListFree (cPrivate->changedSettings, FALSE);
 }
 
 void
@@ -2330,9 +2497,9 @@
 	if (!(*cPrivate->backend->vTable->writeInit) (context))
 	    return;
 
-    if (ccsSettingListLength (context->changedSettings))
+    if (ccsSettingListLength (cPrivate->changedSettings))
     {
-	CCSSettingList l = context->changedSettings;
+	CCSSettingList l = cPrivate->changedSettings;
 
 	while (l)
 	{
@@ -2344,8 +2511,8 @@
     if (cPrivate->backend->vTable->writeDone)
 	(*cPrivate->backend->vTable->writeDone) (context);
 
-    context->changedSettings =
-	ccsSettingListFree (context->changedSettings, FALSE);
+    cPrivate->changedSettings =
+	ccsSettingListFree (cPrivate->changedSettings, FALSE);
 }
 
 Bool
@@ -2409,6 +2576,8 @@
     /* look if the plugin to be loaded requires a plugin not present */
     sl = plugin->requiresPlugin;
 
+    CONTEXT_PRIV (context);
+
     while (sl)
     {
 	if (!ccsFindPlugin (context, ((CCSString *)sl->data)->value))
@@ -2449,7 +2618,7 @@
 
     while (sl)
     {
-	pl = context->plugins;
+	pl = cPrivate->plugins;
 	pl2 = NULL;
 
 	while (pl)
@@ -2505,7 +2674,7 @@
     sl = plugin->providesFeature;
     while (sl)
     {
-	pl = context->plugins;
+	pl = cPrivate->plugins;
 	CCSPluginConflict *conflict = NULL;
 
 	while (pl)
@@ -2549,7 +2718,7 @@
     sl = plugin->conflictFeature;
     while (sl)
     {
-	pl = context->plugins;
+	pl = cPrivate->plugins;
 	CCSPluginConflict *conflict = NULL;
 
 	while (pl)
@@ -2623,8 +2792,10 @@
     CCSPluginList pl;
     CCSStringList sl;
 
+    CONTEXT_PRIV (context);
+
     /* look if the plugin to be unloaded is required by another plugin */
-    pl = context->plugins;
+    pl = cPrivate->plugins;
 
     for (; pl; pl = pl->next)
     {
@@ -2672,7 +2843,7 @@
     sl = plugin->providesFeature;
     while (sl)
     {
-	pl = context->plugins;
+	pl = cPrivate->plugins;
 	for (; pl; pl = pl->next)
 	{
 	    CCSStringList pluginList;
@@ -2901,7 +3072,9 @@
     if (!exportFile)
 	return FALSE;
 
-    for (p = context->plugins; p; p = p->next)
+    CONTEXT_PRIV (context);
+
+    for (p = cPrivate->plugins; p; p = p->next)
     {
 	plugin = p->data;
 	PLUGIN_PRIV (plugin);
@@ -2917,7 +3090,7 @@
 		continue;
 
 	    asprintf (&keyName, "s%d_%s", 
-		      context->screenNum, setting->name);
+		      cPrivate->screenNum, setting->name);
 
 	    switch (setting->type)
 	    {
@@ -2996,7 +3169,9 @@
     char         *sectionName = strdup (setting->parent->name);
     char         *iniValue = NULL;
 
-    asprintf (&keyName, "+s%d_%s", context->screenNum, setting->name);
+    CONTEXT_PRIV (context);
+
+    asprintf (&keyName, "+s%d_%s", cPrivate->screenNum, setting->name);
     if (ccsIniGetString (dict, sectionName, keyName, &iniValue))
     {
 	CCSSetting *newSetting = malloc (sizeof (CCSSetting));
@@ -3148,7 +3323,9 @@
     char         *sectionName = strdup (setting->parent->name);
     char         *iniValue = NULL;
 
-    asprintf (&keyName, "-s%d_%s", context->screenNum, setting->name);
+    CONTEXT_PRIV (context);
+
+    asprintf (&keyName, "-s%d_%s", cPrivate->screenNum, setting->name);
     if (ccsIniGetString (dict, sectionName, keyName, &iniValue))
     {
 	CCSSetting *newSetting = malloc (sizeof (CCSSetting));
@@ -3294,8 +3471,10 @@
 ccsProcessUpgrade (CCSContext *context,
 		   CCSSettingsUpgrade *upgrade)
 {
+    CONTEXT_PRIV (context);
+
     IniDictionary      *dict = ccsIniOpen (upgrade->file);
-    CCSPluginList      pl = context->plugins;
+    CCSPluginList      pl = cPrivate->plugins;
     CCSSettingList     sl;
 
     ccsSetProfile (context, upgrade->profile);
@@ -3702,7 +3881,9 @@
     if (!importFile)
 	return FALSE;
 
-    for (p = context->plugins; p; p = p->next)
+    CONTEXT_PRIV (context);
+
+    for (p = cPrivate->plugins; p; p = p->next)
     {
 	plugin = p->data;
 	PLUGIN_PRIV (plugin);
@@ -3717,7 +3898,7 @@
 		continue;
 
 	    asprintf (&keyName, "s%d_%s", 
-		      context->screenNum, setting->name);
+		      cPrivate->screenNum, setting->name);
 
 	    switch (setting->type)
 	    {
@@ -3905,3 +4086,7 @@
     return pPrivate->stringExtensions;
 }
 
+const CCSInterfaceTable ccsDefaultInterfaceTable =
+{
+    &ccsDefaultContextInterface
+};