Given the following definition:
std::vector< std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> > >
PairsVector;
What is the best way to insert objects into the vector (without creating
them separately before inserting them)? I tried the following, but the
compiler complains that it cannot find a matching constructor:
PairsVector.pus h_back( std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> >( new Class1( NULL ),
new Class2( NULL ) ) );
On the other hand, this does compile:
PairsVector.pus h_back( std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> >( boost::shared_p tr<Class1>(new Class1( NULL )),
boost::shared_p tr<Class2>(new Class2( NULL )) ) );
Why won't the pair<> constructor accept the raw pointers and simply assign
them to the shared_ptr's?
- Dennis 4 3415
Dennis Jones wrote: Given the following definition:
std::vector< std::pair< boost::shared_p tr<Class1>, boost::shared_p tr<Class2> > > PairsVector;
What is the best way to insert objects into the vector (without creating them separately before inserting them)? I tried the following, but the compiler complains that it cannot find a matching constructor:
PairsVector.pus h_back( std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> >( new Class1( NULL ),
new Class2( NULL ) ) );
On the other hand, this does compile:
PairsVector.pus h_back( std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> >( boost::shared_p tr<Class1>(new Class1( NULL )),
boost::shared_p tr<Class2>(new Class2( NULL )) ) );
Why won't the pair<> constructor accept the raw pointers and simply assign them to the shared_ptr's?
Could it be that 'shared_ptr's constructor is _explicit_?
V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
Dennis Jones wrote: Given the following definition:
std::vector< std::pair< boost::shared_p tr<Class1>, boost::shared_p tr<Class2> > > PairsVector;
What is the best way to insert objects into the vector (without creating them separately before inserting them)? I tried the following, but the compiler complains that it cannot find a matching constructor:
PairsVector.pus h_back( std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> >( new Class1( NULL ),
new Class2( NULL ) ) );
On the other hand, this does compile:
PairsVector.pus h_back( std::pair< boost::shared_p tr<Class1>,
boost::shared_p tr<Class2> >( boost::shared_p tr<Class1>(new Class1( NULL )),
boost::shared_p tr<Class2>(new Class2( NULL )) ) );
Why won't the pair<> constructor accept the raw pointers and simply assign them to the shared_ptr's?
Because boost::shared_p tr's constructor is declared as 'explicit' to avoid
the dangers of implicit conversion. Try:
typedef boost::shared_p tr<Class1> tPtr1;
typedef boost::shared_p tr<Class2> tPtr2;
typedef std::pair<tPtr1 ,tPtr2> tPtrPair;
typedef std::vector< tPtrPair > tPtrPairVector;
tPtrPairVector PtrPairVector;
PtrPairVector.p ush_back( tPtrPair( tPtr1( new Class1(NULL) )
, tPtr2( new Class2(NULL) )
)
);
If you find yourself doing this a lot, it may be worth adding a
static Ptr function to your Class1 and Class2 classes.
class Class1
{
....
Class1( int aInt ).... // make private
public:
typedef boost::shared_p tr<Class1> tPtr;
static tPtr Ptr( int aInt ){ return tPtr( new Class1( aInt ); }
};
Ditto for Class2,
Then the push_back above is called like:
PtrPairVector.p ushBack( tPtrPair( Class1::Ptr(NUL L), Class2::Ptr(NUL L) ) );
Jeff Flinn
"Victor Bazarov" <v.********@com Acast.net> wrote in message
news:e1******** **@news.datemas .de... Why won't the pair<> constructor accept the raw pointers and simply assign them to the shared_ptr's?
Could it be that 'shared_ptr's constructor is _explicit_?
Duh, of course!!! I know what an explicit constructor is, but I've only
used one in my own classes once before, so it never even entered my mind.
Thank you!
- Dennis
Dennis Jones wrote: Why won't the pair<> constructor accept the raw pointers and simply assign them to the shared_ptr's?
Because the shared_ptr constructor that takes a raw pointer is explicit.
It won't be called for an implicit conversion.
--
Pete Becker
Roundhouse Consulting, Ltd. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: JKop |
last post by:
What's the difference between them?
Take the following:
#include <iostream>
struct Blah
{
int k;
|
by: Sacha Schär |
last post by:
Suppose I have an array of Foo's:
class Foo
{
public:
int SomeMethode(void);
int i;
char c;
char * p;
|
by: Frank |
last post by:
Hi,
classTeacher contains a list of classChild
ClassChild contains methods, props and so on
Most things a classChild can do on its own.
But AskPermission cannot be done by the Child, but must be done by the
teacher.
Child has to ask its teacher to do that.
Is it a proper OO way to have a reference to the teacher to call a
teachermethod?
Thanks
|
by: bob |
last post by:
Let's say that a class only allows proper initialization through
its constructor. Let's also say that you need a global variable of
that class,
but you can't initialize it at the beginning of the program.
What is the most practical solution?
|
by: Christoph Zwerschke |
last post by:
Usually, you initialize class variables like that:
class A:
sum = 45
But what is the proper way to initialize class variables if they are the
result of some computation or processing as in the following silly
example (representative for more:
class A:
| |
by: lovecreatesbea... |
last post by:
K&R 2, sec 2.4 says: If the variable in question is not automatic, the
initialization is done once only, conceptually before the program
starts executing, ... .
"Non-automatic variables are initialized before the program starts
executing." -- What does this mean? What is the name of the stage in
which the mentioned initialization is performed? Compile-time or
run-time?
In the following snippet, variables b and c are defined at line 7...
|
by: Jess |
last post by:
Hello,
I understand the default-initialization happens if we don't initialize
an object explicitly. I think for an object of a class type, the
value is determined by the constructor, and for the built-in types,
the value is usually garbage. Is this right?
However, I'm a bit confused about value-initialization, when does it
happen, and what kind of values are assigned to objects?
|
by: Jess |
last post by:
Hello,
I tried several books to find out the details of object
initialization. Unfortunately, I'm still confused by two specific
concepts, namely default-initialization and value-initialization. I
think default-init calls default constructor for class objects and
sets garbage values to PODs. Value-init also calls default
constructor for class objects and sets 0s to POD types. This is what
I've learned from the books (especially...
|
by: JohnQ |
last post by:
The way I understand the startup of a C++ program is:
A.) The stuff that happens before the entry point.
B.) The stuff that happens between the entry point and the calling of
main().
C.) main().
So, if the above is OK, does static initialization occur during A or B? What
happens during A?
|
by: subramanian100in |
last post by:
Suppose we have a class named Test.
Test obj; // assuming default ctor is available
Test direct_init(obj); // direct initialization happens here
Test copy_init = obj; // copy initialization happens here
Suppose we have a function
void fn(Test arg);
|
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: 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: 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: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
| |
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: 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...
| |