PgContext

The Pango rendering pipeline takes a string of Unicode characters and converts it into glyphs. The functions described in this section accomplish various steps of this process.

class PgContext : ObjectG {}

Constructors

this
this(PangoContext* pangoContext)

Sets our main struct and passes it to the parent class

this
this()

Creates a new PangoContext initialized to default values. This function is not particularly useful as it should always be followed by a pango_context_set_font_map() call, and the function pango_font_map_create_context() does these two steps together and hence users are recommended to use that. If you are using Pango as part of a higher-level system, that system may have it's own way of create a PangoContext. For instance, the GTK+ toolkit has, among others, gdk_pango_context_get_for_screen(), and gtk_widget_get_pango_context(). Use those instead.

Members

Functions

changed
void changed()

Forces a change in the context, which will cause any PangoLayout using this context to re-layout. This function is only useful when implementing a new backend for Pango, something applications won't do. Backends should call this function if they have attached extra data to the context and such data is changed. Since 1.32.4

getBaseDir
PangoDirection getBaseDir()

Retrieves the base direction for the context. See pango_context_set_base_dir().

getBaseGravity
PangoGravity getBaseGravity()

Retrieves the base gravity for the context. See pango_context_set_base_gravity(). Since 1.16

getFontDescription
PgFontDescription getFontDescription()

Retrieve the default font description for the context.

getFontMap
PgFontMap getFontMap()

Gets the PangoFontmap used to look up fonts for this context. Since 1.6

getGravity
PangoGravity getGravity()

Retrieves the gravity for the context. This is similar to pango_context_get_base_gravity(), except for when the base gravity is PANGO_GRAVITY_AUTO for which pango_gravity_get_for_matrix() is used to return the gravity from the current context matrix. Since 1.16

getGravityHint
PangoGravityHint getGravityHint()

Retrieves the gravity hint for the context. See pango_context_set_gravity_hint() for details. Since 1.16

getLanguage
PgLanguage getLanguage()

Retrieves the global language tag for the context.

getMatrix
PgMatrix getMatrix()

Gets the transformation matrix that will be applied when rendering with this context. See pango_context_set_matrix(). Since 1.6

getMetrics
PgFontMetrics getMetrics(PgFontDescription desc, PgLanguage language)

Get overall metric information for a particular font description. Since the metrics may be substantially different for different scripts, a language tag can be provided to indicate that the metrics should be retrieved that correspond to the script(s) used by that language. The PangoFontDescription is interpreted in the same way as by pango_itemize(), and the family name may be a comma separated list of figures. If characters from multiple of these families would be used to render the string, then the returned fonts would be a composite of the metrics for the fonts loaded for the individual families.

getPgContextStruct
PangoContext* getPgContextStruct()

Get the main Gtk struct

getSerial
uint getSerial()

Returns the current serial number of context. The serial number is initialized to an small number larger than zero when a new context is created and is increased whenever the context is changed using any of the setter functions, or the PangoFontMap it uses to find fonts has changed. The serial may wrap, but will never have the value 0. Since it can wrap, never compare it with "less than", always use "not equals". This can be used to automatically detect changes to a PangoContext, and is only useful when implementing objects that need update when their PangoContext changes, like PangoLayout. Since 1.32.4

getStruct
void* getStruct()

the main Gtk struct as a void*

itemize
ListG itemize(string text, int startIndex, int length, PgAttributeList attrs, PgAttributeIterator cachedIter)

Breaks a piece of text into segments with consistent directional level and shaping engine. Each byte of text will be contained in exactly one of the items in the returned list; the generated list of items will be in logical order (the start offsets of the items are ascending). cached_iter should be an iterator over attrs currently positioned at a range before or containing start_index; cached_iter will be advanced to the range covering the position just after start_index + length. (i.e. if itemizing in a loop, just keep passing in the same cached_iter).

itemizeWithBaseDir
ListG itemizeWithBaseDir(PangoDirection baseDir, string text, int startIndex, int length, PgAttributeList attrs, PgAttributeIterator cachedIter)

Like pango_itemize(), but the base direction to use when computing bidirectional levels (see pango_context_set_base_dir()), is specified explicitly rather than gotten from the PangoContext. Since 1.4

listFamilies
void listFamilies(PgFontFamily[] families)

List all families for a context.

loadFont
PgFont loadFont(PgFontDescription desc)

Loads the font in one of the fontmaps in the context that is the closest match for desc.

loadFontset
PgFontset loadFontset(PgFontDescription desc, PgLanguage language)

Load a set of fonts in the context that can be used to render a font matching desc.

setBaseDir
void setBaseDir(PangoDirection direction)

Sets the base direction for the context. The base direction is used in applying the Unicode bidirectional algorithm; if the direction is PANGO_DIRECTION_LTR or PANGO_DIRECTION_RTL, then the value will be used as the paragraph direction in the Unicode bidirectional algorithm. A value of PANGO_DIRECTION_WEAK_LTR or PANGO_DIRECTION_WEAK_RTL is used only for paragraphs that do not contain any strong characters themselves.

setBaseGravity
void setBaseGravity(PangoGravity gravity)

Sets the base gravity for the context. The base gravity is used in laying vertical text out. Since 1.16

setFontDescription
void setFontDescription(PgFontDescription desc)

Set the default font description for the context

setFontMap
void setFontMap(PgFontMap fontMap)

Sets the font map to be searched when fonts are looked-up in this context. This is only for internal use by Pango backends, a PangoContext obtained via one of the recommended methods should already have a suitable font map.

setGravityHint
void setGravityHint(PangoGravityHint hint)

Sets the gravity hint for the context. The gravity hint is used in laying vertical text out, and is only relevant if gravity of the context as returned by pango_context_get_gravity() is set PANGO_GRAVITY_EAST or PANGO_GRAVITY_WEST. Since 1.16

setLanguage
void setLanguage(PgLanguage language)

Sets the global language tag for the context. The default language for the locale of the running process can be found using pango_language_get_default().

setMatrix
void setMatrix(PgMatrix matrix)

Sets the transformation matrix that will be applied when rendering with this context. Note that reported metrics are in the user space coordinates before the application of the matrix, not device-space coordinates after the application of the matrix. So, they don't scale with the matrix, though they may change slightly for different matrices, depending on how the text is fit to the pixel grid. Since 1.6

setStruct
void setStruct(GObject* obj)
Undocumented in source. Be warned that the author may not have intended to support it.

Static functions

bidiTypeForUnichar
PangoBidiType bidiTypeForUnichar(gunichar ch)

Determines the normative bidirectional character type of a character, as specified in the Unicode Character Database. A simplified version of this function is available as pango_unichar_get_direction(). Since 1.22

defaultBreak
void defaultBreak(string text, int length, PangoAnalysis* analysis, PangoLogAttr* attrs, int attrsLen)

This is the default break algorithm, used if no language engine overrides it. Normally you should use pango_break() instead. Unlike pango_break(), analysis can be NULL, but only do that if you know what you're doing. If you need an analysis to pass to pango_break(), you need to pango_itemize(). In most cases however you should simply use pango_get_log_attrs().

findBaseDir
PangoDirection findBaseDir(string text, int length)

Searches a string the first character that has a strong direction, according to the Unicode bidirectional algorithm. Since 1.4

findParagraphBoundary
void findParagraphBoundary(string text, int length, int paragraphDelimiterIndex, int nextParagraphStart)

Locates a paragraph boundary in text. A boundary is caused by delimiter characters, such as a newline, carriage return, carriage return-newline pair, or Unicode paragraph separator character. The index of the run of delimiters is returned in paragraph_delimiter_index. The index of the start of the paragraph (index after all delimiters) is stored in next_paragraph_start. If no delimiters are found, both paragraph_delimiter_index and next_paragraph_start are filled with the length of text (an index one off the end).

getLogAttrs
void getLogAttrs(string text, int length, int level, PgLanguage language, PangoLogAttr* logAttrs, int attrsLen)

Computes a PangoLogAttr for each character in text. The log_attrs array must have one PangoLogAttr for each position in text; if text contains N characters, it has N+1 positions, including the last position at the end of the text. text should be an entire paragraph; logical attributes can't be computed without context (for example you need to see spaces on either side of a word to know the word is a word).

getMirrorChar
int getMirrorChar(gunichar ch, gunichar* mirroredCh)

Warning pango_get_mirror_char is deprecated and should not be used in newly-written code. If ch has the Unicode mirrored property and there is another Unicode character that typically has a glyph that is the mirror image of ch's glyph, puts that character in the address pointed to by mirrored_ch. Use g_unichar_get_mirror_char() instead; the docs for that function provide full details.

pangoBreak
void pangoBreak(string text, int length, PangoAnalysis* analysis, PangoLogAttr* attrs, int attrsLen)

Determines possible line, word, and character breaks for a string of Unicode text with a single analysis. For most purposes you may want to use pango_get_log_attrs().

reorderItems
ListG reorderItems(ListG logicalItems)

From a list of items in logical order and the associated directional levels, produce a list in visual order. The original list is unmodified.

shape
void shape(string text, int length, PangoAnalysis* analysis, PgGlyphString glyphs)

Given a segment of text and the corresponding PangoAnalysis structure returned from pango_itemize(), convert the characters into glyphs. You may also pass in only a substring of the item from pango_itemize(). It is recommended that you use pango_shape_full() instead, since that API allows for shaping interaction happening across text item boundaries.

shapeFull
void shapeFull(string itemText, string paragraphText, PangoAnalysis* analysis, PgGlyphString glyphs)

Given a segment of text and the corresponding PangoAnalysis structure returned from pango_itemize(), convert the characters into glyphs. You may also pass in only a substring of the item from pango_itemize(). This is similar to pango_shape(), except it also can optionally take the full paragraph text as input, which will then be used to perform certain cross-item shaping interactions. If you have access to the broader text of which item_text is part of, provide the broader text as paragraph_text. If paragraph_text is NULL, item text is used instead. Since 1.32

unicharDirection
PangoDirection unicharDirection(gunichar ch)

Determines the inherent direction of a character; either PANGO_DIRECTION_LTR, PANGO_DIRECTION_RTL, or PANGO_DIRECTION_NEUTRAL. This function is useful to categorize characters into left-to-right letters, right-to-left letters, and everything else. If full Unicode bidirectional type of a character is needed, pango_bidi_type_for_gunichar() can be used instead.

Variables

pangoContext
PangoContext* pangoContext;

the main Gtk struct

Inherited Members

From ObjectG

gObject
GObject* gObject;

the main Gtk struct

getObjectGStruct
GObject* getObjectGStruct()

Get the main Gtk struct

getStruct
void* getStruct()

the main Gtk struct as a void*

isGcRoot
bool isGcRoot;
Undocumented in source.
destroyNotify
void destroyNotify(ObjectG obj)
Undocumented in source. Be warned that the author may not have intended to support it.
toggleNotify
void toggleNotify(ObjectG obj, GObject* object, int isLastRef)
Undocumented in source. Be warned that the author may not have intended to support it.
~this
~this()
Undocumented in source.
getDObject
RT getDObject(U obj)

Gets a D Object from the objects table of associations.

setStruct
void setStruct(GObject* obj)
Undocumented in source. Be warned that the author may not have intended to support it.
setProperty
void setProperty(string propertyName, int value)
setProperty
void setProperty(string propertyName, string value)
setProperty
void setProperty(string propertyName, long value)
setProperty
void setProperty(string propertyName, ulong value)
unref
void unref()
Undocumented in source. Be warned that the author may not have intended to support it.
doref
ObjectG doref()
Undocumented in source. Be warned that the author may not have intended to support it.
connectedSignals
int[string] connectedSignals;
Undocumented in source.
onNotifyListeners
void delegate(ParamSpec, ObjectG)[] onNotifyListeners;
Undocumented in source.
addOnNotify
void addOnNotify(void delegate(ParamSpec, ObjectG) dlg, string property, ConnectFlags connectFlags)

The notify signal is emitted on an object when one of its properties has been changed. Note that getting this signal doesn't guarantee that the value of the property has actually changed, it may also be emitted when the setter for the property is called to reinstate the previous value.

callBackNotify
void callBackNotify(GObject* gobjectStruct, GParamSpec* pspec, ObjectG _objectG)
Undocumented in source. Be warned that the author may not have intended to support it.
classInstallProperty
void classInstallProperty(GObjectClass* oclass, uint propertyId, ParamSpec pspec)

Installs a new property. This is usually done in the class initializer. Note that it is possible to redefine a property in a derived class, by installing a property with the same name. This can be useful at times, e.g. to change the range of allowed values or the default value.

classInstallProperties
void classInstallProperties(GObjectClass* oclass, ParamSpec[] pspecs)

Installs new properties from an array of GParamSpecs. This is usually done in the class initializer. The property id of each property is the index of each GParamSpec in the pspecs array. The property id of 0 is treated specially by GObject and it should not be used to store a GParamSpec. This function should be used if you plan to use a static array of GParamSpecs and g_object_notify_by_pspec(). For instance, this Since 2.26

classFindProperty
ParamSpec classFindProperty(GObjectClass* oclass, string propertyName)

Looks up the GParamSpec for a property of a class.

classListProperties
ParamSpec[] classListProperties(GObjectClass* oclass)

Get an array of GParamSpec* for all properties of a class.

classOverrideProperty
void classOverrideProperty(GObjectClass* oclass, uint propertyId, string name)

Registers property_id as referring to a property with the name name in a parent class or in an interface implemented by oclass. This allows this class to override a property implementation in a parent class or to provide the implementation of a property from an interface. Note Internally, overriding is implemented by creating a property of type GParamSpecOverride; generally operations that query the properties of the object class, such as g_object_class_find_property() or g_object_class_list_properties() will return the overridden property. However, in one case, the construct_properties argument of the constructor virtual function, the GParamSpecOverride is passed instead, so that the param_id field of the GParamSpec will be correct. For virtually all uses, this makes no difference. If you need to get the overridden property, you can call g_param_spec_get_redirect_target(). Since 2.4

interfaceInstallProperty
void interfaceInstallProperty(void* iface, ParamSpec pspec)

Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created GParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property. This function is meant to be called from the interface's default vtable initialization function (the class_init member of GTypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface. Since 2.4

interfaceFindProperty
ParamSpec interfaceFindProperty(void* iface, string propertyName)

Find the GParamSpec with the given name for an interface. Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek(). Since 2.4

interfaceListProperties
ParamSpec[] interfaceListProperties(void* iface)

Lists the properties of an interface.Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek(). Since 2.4

doref
void* doref(void* object)

Increases the reference count of object.

unref
void unref(void* object)

Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).

refSink
void* refSink(void* object)

Increase the reference count of object, and possibly remove the floating reference, if object has a floating reference. In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one. Since 2.10

clearObject
void clearObject(ObjectG objectPtr)

Clears a reference to a GObject. object_ptr must not be NULL. If the reference is NULL then this function does nothing. Otherwise, the reference count of the object is decreased and the pointer is set to NULL. This function is threadsafe and modifies the pointer atomically, using memory barriers where needed. A macro is also included that allows this function to be used without pointer casts. Since 2.28

isFloating
int isFloating(void* object)

Checks whether object has a floating reference. Since 2.10

forceFloating
void forceFloating()

This function is intended for GObject implementations to re-enforce a floating object reference. Doing this is seldom required: all GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink(). Since 2.10

weakRef
void weakRef(GWeakNotify notify, void* data)

Adds a weak reference callback to an object. Weak references are used for notification when an object is finalized. They are called "weak references" because they allow you to safely hold a pointer to an object without calling g_object_ref() (g_object_ref() adds a strong reference, that is, forces the object to stay alive). Note that the weak references created by this method are not thread-safe: they cannot safely be used in one thread if the object's last g_object_unref() might happen in another thread. Use GWeakRef if thread-safety is required.

weakUnref
void weakUnref(GWeakNotify notify, void* data)

Removes a weak reference callback to an object.

addWeakPointer
void addWeakPointer(void** weakPointerLocation)

Adds a weak reference from weak_pointer to object to indicate that the pointer located at weak_pointer_location is only valid during the lifetime of object. When the object is finalized, weak_pointer will be set to NULL. Note that as with g_object_weak_ref(), the weak references created by this method are not thread-safe: they cannot safely be used in one thread if the object's last g_object_unref() might happen in another thread. Use GWeakRef if thread-safety is required.

removeWeakPointer
void removeWeakPointer(void** weakPointerLocation)

Removes a weak reference from object that was previously added using g_object_add_weak_pointer(). The weak_pointer_location has to match the one used with g_object_add_weak_pointer().

addToggleRef
void addToggleRef(GToggleNotify notify, void* data)

Increases the reference count of the object by one and sets a callback to be called when all other references to the object are dropped, or when this is already the last reference to the object and another reference is established. This functionality is intended for binding object to a proxy object managed by another memory manager. This is done with two paired references: the strong reference added by g_object_add_toggle_ref() and a reverse reference to the proxy object which is either a strong reference or weak reference. The setup is that when there are no other references to object, only a weak reference is held in the reverse direction from object to the proxy object, but when there are other references held to object, a strong reference is held. The notify callback is called when the reference from object to the proxy object should be toggled from strong to weak (is_last_ref true) or weak to strong (is_last_ref false). Since a (normal) reference must be held to the object before calling g_object_add_toggle_ref(), the initial state of the reverse link is always strong. Multiple toggle references may be added to the same gobject, however if there are multiple toggle references to an object, none of them will ever be notified until all but one are removed. For this reason, you should only ever use a toggle reference if there is important state in the proxy object. Since 2.8

removeToggleRef
void removeToggleRef(GToggleNotify notify, void* data)

Removes a reference added with g_object_add_toggle_ref(). The reference count of the object is decreased by one. Since 2.8

notify
void notify(string propertyName)

Emits a "notify" signal for the property property_name on object. When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

notifyByPspec
void notifyByPspec(ParamSpec pspec)

Emits a "notify" signal for the property specified by pspec on object. This function omits the property name lookup, hence it is faster than g_object_notify(). One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with Since 2.26

freezeNotify
void freezeNotify()

Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one "notify" signal is emitted for each property modified while the object is frozen. This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.

thawNotify
void thawNotify()

Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted. Duplicate notifications for each property are squashed so that at most one "notify" signal is emitted for each property. It is an error to call this function when the freeze count is zero.

getData
void* getData(string key)

Gets a named field from the objects table of associations (see g_object_set_data()).

setData
void setData(string key, void* data)

Each object carries around a table of associations from strings to pointers. This function lets you set an association. If the object already had an association with that name, the old association will be destroyed.

setDataFull
void setDataFull(string key, void* data, GDestroyNotify destroy)

Like g_object_set_data() except it adds notification for when the association is destroyed, either by setting it to a different value or when the object is destroyed. Note that the destroy callback is not called if data is NULL.

stealData
void* stealData(string key)

Remove a specified datum from the object's data associations, without invoking the association's destroy handler.

dupData
void* dupData(string key, GDuplicateFunc dupFunc, void* userData)

This is a variant of g_object_get_data() which returns a 'duplicate' of the value. dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object. If the key is not set on the object then dup_func will be called with a NULL argument. Note that dup_func is called while user data of object is locked. This function can be useful to avoid races when multiple threads are using object data on the same key on the same object. Since 2.34

replaceData
int replaceData(string key, void* oldval, void* newval, GDestroyNotify destroy, GDestroyNotify* oldDestroy)

Compares the user data for the key key on object with oldval, and if they are the same, replaces oldval with newval. This is like a typical atomic compare-and-exchange operation, for user data on an object. If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registered destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way. Return: TRUE if the existing value for key was replaced by newval, FALSE otherwise. Since 2.34

getQdata
void* getQdata(GQuark quark)

This function gets back user data pointers stored via g_object_set_qdata().

setQdata
void setQdata(GQuark quark, void* data)

This sets an opaque, named pointer on an object. The name is specified through a GQuark (retrived e.g. via g_quark_from_static_string()), and the pointer can be gotten back from the object with g_object_get_qdata() until the object is finalized. Setting a previously set user data pointer, overrides (frees) the old pointer set, using NULL as pointer essentially removes the data stored.

setQdataFull
void setQdataFull(GQuark quark, void* data, GDestroyNotify destroy)

This function works like g_object_set_qdata(), but in addition, a void (*destroy) (gpointer) function may be specified which is called with data as argument when the object is finalized, or the data is being overwritten by a call to g_object_set_qdata() with the same quark.

stealQdata
void* stealQdata(GQuark quark)

This function gets back user data pointers stored via g_object_set_qdata() and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update

dupQdata
void* dupQdata(GQuark quark, GDuplicateFunc dupFunc, void* userData)

This is a variant of g_object_get_qdata() which returns a 'duplicate' of the value. dup_func defines the meaning of 'duplicate' in this context, it could e.g. take a reference on a ref-counted object. If the quark is not set on the object then dup_func will be called with a NULL argument. Note that dup_func is called while user data of object is locked. This function can be useful to avoid races when multiple threads are using object data on the same key on the same object. Since 2.34

replaceQdata
int replaceQdata(GQuark quark, void* oldval, void* newval, GDestroyNotify destroy, GDestroyNotify* oldDestroy)

Compares the user data for the key quark on object with oldval, and if they are the same, replaces oldval with newval. This is like a typical atomic compare-and-exchange operation, for user data on an object. If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registered destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way. Return: TRUE if the existing value for quark was replaced by newval, FALSE otherwise. Since 2.34

setProperty
void setProperty(string propertyName, Value value)

Sets a property on an object.

getProperty
void getProperty(string propertyName, Value value)

Gets a property of an object. value must have been initialized to the expected type of the property (or a type to which the expected type can be transformed) using g_value_init(). In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset(). Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.

setValist
void setValist(string firstPropertyName, void* varArgs)

Sets properties on an object.

getValist
void getValist(string firstPropertyName, void* varArgs)

Gets properties of an object. In general, a copy is made of the property contents and the caller is responsible for freeing the memory in the appropriate manner for the type, for instance by calling g_free() or g_object_unref(). See g_object_get().

watchClosure
void watchClosure(Closure closure)

This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling g_closure_invalidate() on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.

runDispose
void runDispose()

Releases all references to other objects. This can be used to break reference cycles. This functions should only be called from object system implementations.

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