Hello all,
I have made a class into a singleton by having a static get() method which
returns a pointer to the one-and-only instance. This method creates the
instance on the heap if it hasn't already done so in a prior call.
Constructors are private so that the class may not be instaniated from
outside. As I understand it, this is the standard approach and is nothing
new.
I have no need to ever destroy this singleton and re-create a new one in
it's place, so I have not provided a method for destruction.
My question is: Where in my code, if ever, should the singleton be
deallocated? Is it standard practice to just ignore this memory, or would
it really be more proper to find some way to deallocate it manually upon
app. exit?
Thanks,
Dave
4  4196 
"Dave" <be***********@ yahoo.com> wrote in message
news:10******** *****@news.supe rnews.com... Hello all,
I have made a class into a singleton by having a static get() method which
returns a pointer to the one-and-only instance. This method creates the
instance on the heap if it hasn't already done so in a prior call.
Constructors are private so that the class may not be instaniated from
outside. As I understand it, this is the standard approach and is nothing
new.
There is another approach, declare the object as static within the get
method. This ensures that it will be destructed on exit.
class X
{
static X& get()
{
static X the_x;
return the_x;
}
};
I have no need to ever destroy this singleton and re-create a new one in
it's place, so I have not provided a method for destruction.
My question is: Where in my code, if ever, should the singleton be
deallocated? Is it standard practice to just ignore this memory, or would
it really be more proper to find some way to deallocate it manually upon
app. exit?
Depends on how good your OS is on reclaiming resources from exited
applications. I don't think operating systems have much problem with memory,
that will automatically be reclaimed. Other resources, well I think you have
to consult your documentation.
The best discussion I know of singletons and the policies you can adopt for
them is in Andrei Alexandrescu's book Modern C++ Design. You can get the
code if not the book online, google for loki library.
john
Thanks,
Dave
"Dave" <be***********@ yahoo.com> wrote in message
news:10******** *****@news.supe rnews.com... Hello all,
I have made a class into a singleton by having a static get() method which
returns a pointer to the one-and-only instance. This method creates the
instance on the heap if it hasn't already done so in a prior call.
Constructors are private so that the class may not be instaniated from
outside. As I understand it, this is the standard approach and is nothing
new.
There is another approach, declare the object as static within the get
method. This ensures that it will be destructed on exit.
class X
{
static X& get()
{
static X the_x;
return the_x;
}
};
I have no need to ever destroy this singleton and re-create a new one in
it's place, so I have not provided a method for destruction.
My question is: Where in my code, if ever, should the singleton be
deallocated? Is it standard practice to just ignore this memory, or would
it really be more proper to find some way to deallocate it manually upon
app. exit?
Depends on how good your OS is on reclaiming resources from exited
applications. I don't think operating systems have much problem with memory,
that will automatically be reclaimed. Other resources, well I think you have
to consult your documentation.
The best discussion I know of singletons and the policies you can adopt for
them is in Andrei Alexandrescu's book Modern C++ Design. You can get the
code if not the book online, google for loki library.
john
Thanks,
Dave
On Thu, 8 Apr 2004 19:30:52 +0100 in comp.lang.c++, "John Harrison"
<jo************ *@hotmail.com> wrote, There is another approach, declare the object as static within the get
method. This ensures that it will be destructed on exit.
And if something requires that the object be allocated with new, that's
a case where a static std::auto_ptr<t > can do the job.
On Thu, 8 Apr 2004 19:30:52 +0100 in comp.lang.c++, "John Harrison"
<jo************ *@hotmail.com> wrote, There is another approach, declare the object as static within the get
method. This ensures that it will be destructed on exit.
And if something requires that the object be allocated with new, that's
a case where a static std::auto_ptr<t > can do the job. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
by: Damon |
last post by:
Hi,
I tried to perform a singleton pattern with lazy instantiation but
keep getting linker errors. Could someone advise what I'm doing
wrongly? I'm using gcc version 3.2.2. Thanks in advance.
--------------linker errors-------------
eve.o(.text+0x366): In function `main':
/usr/include/c++/3.2.2/i386-slackware-linux/bits/atomicity.h:50:
undefined reference to `eve::sq_note::sq_note()'
|
by: Dave |
last post by:
Hello all,
I have made a class into a singleton by having a static get() method which
returns a pointer to the one-and-only instance. This method creates the
instance on the heap if it hasn't already done so in a prior call.
Constructors are private so that the class may not be instaniated from
outside. As I understand it, this is the standard approach and is nothing
new.
I have no need to ever destroy this singleton and re-create a...
|
by: JSheble |
last post by:
I understand the difference between the two types (Singleton & SingleCall)
but what affect does this have if the Remoting Server accepts multiple
connections from multiple clients, and they're all sending messages or using
methods? Does it (server) manage this automatically?
|
by: tomgee |
last post by:
I saw it many times,
// T.h:
class T
{
public:
static T* instance();
private:
T() {}
|
by: toton |
last post by:
Hi,
If I have a singleton class based on dynamic initialization (with new
) , is it considered a memory leak? Anything in C++ standard says about
it ?
And little off - topic question ,
If the singleton is initialized as a static variable , it seems
there is some threading issue . Is it the issue during singleton
initialization only , or during the access also?
If the singleton is per thread basis (then no more singleton though
), and...
| | |
by: wkaras |
last post by:
Why aren't "Singletons" done like this in C++:
A.hpp:
class A
{
public: static A theA;
// ...
|
by: EvilOldGit |
last post by:
In the stuff I've read about multi threaded singleton it seems to
assume that creating the Lock is atomic, and various sources,
including Sutter go for RAII.
{
Lock l;
if ( ! inst )....
}
But I don't see how to do this with a real O/S API.
The ones I've looked at have a two step process to making a lock, they
require a "Create" function and a "Start Locking" function.
|
by: Eric |
last post by:
I created a singleton class as in the example below. The application
sporadically crashes in the second line of the main function as shown.
However, when I change the singleton such that the static pointer is a
class member (defined in the cpp file) and the instance function
creates the object if the pointer is NULL, then it works fine. I would
appreciate any explanations as to why this happens.
class CTestClass
{
public:
|
by: Stephen Torri |
last post by:
I am trying to produce a singleton class that I can use throughout my
library to write tracing information to a file. My intent was to design
such that someone using the library in its debug mode would be able to
see what was happening without having to use a debugger to step through
each instruction. What they would do is run their program and view the
tracing file output. If there was something wrong then they would use the
debugger of...
|
by: weaknessforcats |
last post by:
Design Pattern: The Singleton
Overview
Use the Singleton Design Pattern when you want to have only one instance of a class. This single instance must have a single global point of access. That is, regardless of where the object is hidden, everyone needs access to it.
The global point of access is the object's Instance() method.
Individual users need to be prevented from creating their own instances of the Singleton.
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
| | |
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
|
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth.
The Art of Business Website Design
Your website is...
|
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules.
He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms.
Adolph will...
|
by: TSSRALBI |
last post by:
Hello
I'm a network technician in training and I need your help.
I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs.
The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols.
I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
| | |
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
| |
