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 4194
"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: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
| |
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: 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: 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: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
|
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: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
| |
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
|
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| |