lazarus/docs/xml/lazutils/lazclasses.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--

Documentation for LCL (Lazarus Component Library) and LazUtils (Lazarus 
Utilities) are published under the Creative Commons Attribution-ShareAlike 4.0 
International public license.

https://creativecommons.org/licenses/by-sa/4.0/legalcode.txt
https://gitlab.com/freepascal.org/lazarus/lazarus/-/blob/main/docs/cc-by-sa-4-0.txt

Copyright (c) 1997-2025, by the Lazarus Development Team.

-->
<fpdoc-descriptions>
<package name="lazutils">
<!--
====================================================================
LazClasses
====================================================================
-->
<module name="LazClasses">
<short>
Contains classes and routines used to implement free notifications and 
reference counting.
</short>
<descr>
<p>
<file>lazclasses.pas</file> is part of the <file>lazutils</file> package.
</p>
</descr>

<!-- unresolved external references -->
<element name="SysUtils"/>
<element name="Classes"/>
<element name="LazMethodList"/>

<element name="TFreeNotifyingGeneric">
<short>
Generic implementation of the class used to implement objects which perform 
free notifications.
</short>
<descr/>
<seealso/>
</element>

<!-- private -->
<element name="TFreeNotifyingGeneric.FFreeNotificationList"/>

<!-- protected -->
<element name="TFreeNotifyingGeneric.DoDestroy">
<short>
Alternate destructor for the generic class type.  
</short>
<descr>
<p>
FPC issues an error and can not compile an overridden Destructor.
</p>
</descr>
<seealso/>
</element>

<!-- public -->
<element name="TFreeNotifyingGeneric.AddFreeNotification">
<short>
Adds the specified notification to the notification list in the generic class instance.
</short>
<descr/>
<seealso/>
</element>
<element name="TFreeNotifyingGeneric.AddFreeNotification.ANotification">
<short>
The notification event handler added to the notification list.
</short>
</element>

<element name="TFreeNotifyingGeneric.RemoveFreeNotification">
<short>
Removes the specified notification from the notification list in the generic class instance.
</short>
<descr/>
<seealso/>
</element>
<element name="TFreeNotifyingGeneric.RemoveFreeNotification.ANotification">
<short>
The notification event handler removed from the notification list.
</short>
</element>

<element name="TFreeNotifyingObject">
<short>
Base class used to implement objects which perform free notifications.
</short>
<descr/>
<seealso/>
</element>

<element name="TFreeNotifyingObject.FFreeNotificationList">
<short>
List of notification methods called when the object is freed.
</short>
</element>

<element name="TFreeNotifyingObject.Destroy">
<short>Destructor for the class instance.</short>
<descr/>
<seealso/>
</element>

<element name="TFreeNotifyingObject.AddFreeNotification">
<short>
Adds the specified method to the notification list in the class instance.
</short>
<descr/>
<seealso/>
</element>
<element name="TFreeNotifyingObject.AddFreeNotification.ANotification">
<short>The notification event handler added to the internal list.</short>
</element>

<element name="TFreeNotifyingObject.RemoveFreeNotification">
<short>Removes the specified method from the internal list.</short>
<descr/>
<seealso/>
</element>
<element name="TFreeNotifyingObject.RemoveFreeNotification.ANotification">
<short>The notification event handler removed from the internal list.</short>
</element>

<element name="TRefCountedObject">
<short>
Implements a thread-safe reference-counted class which performs free 
notifications.
</short>
<descr>
<p>
Used in the implementation of logging classes and the debugger interface in 
Lazarus. Also used in the implementation of classes for TSynEdit.
</p>
</descr>
<seealso/>
</element>

<!-- private -->
<element name="TRefCountedObject.FRefCount"/>
<element name="TRefCountedObject.FIncDecRefCount"/>
<element name="TRefCountedObject.FDebugNext"/>
<element name="TRefCountedObject.FDebugPrev"/>
<element name="TRefCountedObject.FDebugList"/>
<element name="TRefCountedObject.FCritSect"/>
<element name="TRefCountedObject.FInDestroy"/>
<element name="TRefCountedObject.DbgAddName"/>
<element name="TRefCountedObject.DbgAddName.DebugIdAdr"/>
<element name="TRefCountedObject.DbgAddName.DebugIdTxt"/>
<element name="TRefCountedObject.DbgRemoveName"/>
<element name="TRefCountedObject.DbgRemoveName.DebugIdAdr"/>
<element name="TRefCountedObject.DbgRemoveName.DebugIdTxt"/>

<element name="TRefCountedObject.DoFree">
<short>
Performs actions needed to free the reference counted object instance.
</short>
<descr>
<p>
Calls the inherited Free method.
</p>
</descr>
<seealso/>
</element>

<element name="TRefCountedObject.DoReferenceAdded">
<short>Has an empty implementation in TRefCountedObject.</short>
<descr/>
<seealso/>
</element>

<element name="TRefCountedObject.DoReferenceReleased">
<short>Has an empty implementation in TRefCountedObject.</short>
<descr/>
<seealso/>
</element>

<element name="TRefCountedObject.RefCount">
<short>
Number of times the object instance has been referenced in the application.
</short>
<descr>
<p>
<var>RefCount</var> is a read-only <var>Integer</var> property which contains 
the number of times the object instance has been referenced. Its value is 
maintained when methods like <var>AddReference</var> and 
<var>ReleaseReference</var> are called.
</p>
</descr>
<seealso>
<link id="TRefCountedObject.AddReference"/>
<link id="TRefCountedObject.ReleaseReference"/>
</seealso>
</element>

<element name="TRefCountedObject.Create">
<short>Constructor for the class instance.</short>
<descr>
<p>
Create is the constructor for the class instance. It sets the default values 
for members used in the class instance.When WITH_REFCOUNT_DEBUG has been 
defined in the LCL, a critical section used during debugging is initialized. 
Create calls the inherited constructor prior to exiting from the method.
</p>
</descr>
<seealso>
<link id="TRefCountedObject.RefCount"/>
</seealso>
</element>

<element name="TRefCountedObject.Destroy">
<short>Destructor for the class instance.</short>
<descr>
<p>
<var>Destroy</var> is the overridden destructor for the class instance. It 
ensures that resource allocated in the constructor are freed before freeing 
the class instance. Destroy calls the inherited destructor prior to exit.
</p>
</descr>
<errors>
Destroy raises an EAssertionFailed exception if RefCount has a non-zero value 
when the method was called.
</errors>
<seealso/>
</element>

<element name="TRefCountedObject.AddReference">
<short>Increments the value in RefCount and calls DoReferenceAdded.</short>
<descr>
<p>
AddReference and ReleaseReference can be used in threads. However a thread 
can only call the methods, if either:
</p>
<ul>
<li>
The thread already holds a reference (and no other thread will release that 
reference).
</li>
<li>
The thread created the reference, and no other thread has access to the 
object (yet).
</li>
<li>
The thread is in a critical section, preventing other threads from decreasing 
the reference count.
</li>
</ul>
</descr>
<seealso/>
</element>
<element name="TRefCountedObject.AddReference.DebugIdAdr">
<short>
Debugging symbol.
</short>
</element>
<element name="TRefCountedObject.AddReference.DebugIdTxt">
<short>
Debugging symbol.
</short>
</element>

<element name="TRefCountedObject.ReleaseReference">
<short>Decrements the value in RefCount and calls DoReferenceReleased.</short>
<descr>
<p>
AddReference and ReleaseReference can be used in threads. However a thread 
can only call the methods, if either:
</p>
<ul>
<li>
The thread already holds a reference (and no other thread will release that 
reference).
</li>
<li>
The thread created the reference, and no other thread has access to the 
object (yet).
</li>
<li>
The thread is in a critical section, preventing other threads from decreasing 
the reference count.
</li>
</ul>
</descr>
<seealso/>
</element>
<element name="TRefCountedObject.ReleaseReference.DebugIdAdr">
<short>
Debugging symbol.
</short>  
</element>
<element name="TRefCountedObject.ReleaseReference.DebugIdTxt">
<short>
Debugging symbol.
</short>
</element>

<element name="TRefCountedObject.DbgRenameReference">
<short>
implemented when WITH_REFCOUNT_DEBUG is defined in the LCL.
</short>
<descr/>
<seealso/>
</element>
<element name="TRefCountedObject.DbgRenameReference.DebugIdAdr">
<short>
Debugging symbol.
</short>
</element>
<element name="TRefCountedObject.DbgRenameReference.DebugIdTxt">
<short>
Debugging symbol.
</short>
</element>
<element name="TRefCountedObject.DbgRenameReference.OldDebugIdAdr">
<short>
Debugging symbol.
</short>
</element>
<element name="TRefCountedObject.DbgRenameReference.OldDebugIdTxt">
<short>
Debugging symbol.
</short>
</element>

<element name="TRefCntObjList">
<short>
Implements a list used to store TRefCountedObject instances.
</short>
<descr>
<p>
Provides a <var>Notify</var> method which increases or decreases the 
reference count for an object when it is added to or removed from the 
list.ist.
</p>
</descr>
<seealso/>
</element>

<element name="TRefCntObjList.Notify">
<short>
Performs a notification when an object is added to or removed from the list.
</short>
<descr>
<p>
For TRefCntObjList, the notification causes the reference count for the 
object in Ptr to be increased or decreased as needed for the value in Action.
</p>
</descr>
<seealso/>
</element>
<element name="TRefCntObjList.Notify.Ptr">
<short>
Pointer to the object instance for the notification.
</short>
</element>
<element name="TRefCntObjList.Notify.Action">
<short>
Identifies the action that caused the list notification.
</short>
</element>

<element name="ReleaseRefAndNil">
<short>
Releases the specified reference counted object and sets it to Nil.
</short>
<descr>
<p>
No actions are performed in the method when ARefCountedObject has not been 
assigned, or has already been released. ReleaseRefAndNil calls the 
ReleaseReference method for the object instance, and sets the pointer in 
ARefCountedObject to Nil.
</p>
</descr>
<errors>
Raises an EAssertionFailed exception if the object instance in 
ARefCountedObject is derived from a class other than TRefCountedObject.
</errors>
<seealso/>
</element>
<element name="ReleaseRefAndNil.ARefCountedObject">
<short>
TRefCountedObject object instance examined and updated in the routine.
</short>
</element>
<element name="ReleaseRefAndNil.DebugIdAdr">
<short>
Debugging symbol.  
</short>
</element>
<element name="ReleaseRefAndNil.DebugIdTxt">
<short>
Debugging symbol.  
</short>
</element>

<element name="NilThenReleaseRef">
<short>
Copies and releases the specified reference counted object, and sets the copy 
to Nil.
</short>
<descr>
<p>
No actions are performed in the method when ARefCountedObject has not been 
assigned, or has already been released. ReleaseRefAndNil calls the 
ReleaseReference method for the object instance, and sets the pointer in 
ARefCountedObject to Nil.
</p>
</descr>
<errors>
Raises an EAssertionFailed exception if the object instance in 
ARefCountedObject is derived from a class other than TRefCountedObject.
</errors>
<seealso/>
</element>
<element name="NilThenReleaseRef.ARefCountedObject">
<short>
TRefCountedObject object instance examined and updated in the routine.
</short>
</element>
<element name="NilThenReleaseRef.DebugIdAdr">
<short>
Debugging symbol.  
</short>
</element>
<element name="NilThenReleaseRef.DebugIdTxt">
<short>
Debugging symbol.  
</short>
</element>

</module>
<!-- LazClasses -->
</package>
</fpdoc-descriptions>