Use this tag for questions related to the 'using' keyword in C++.
Questions tagged [using-declaration]
164 questions
1
vote
0 answers
Alias for user defined literal, i.e. 'using NS::operator ""_suffix' with another name
Consider that some library defines:
namespace NS {
constexpr atype operator ""_suffix(const char*, std::size_t);
};
If I don't like the name _suffix (maybe it clashes with some other library, or it is in stark contrast with my naming…
Kijewski
- 25,517
- 12
- 101
- 143
1
vote
2 answers
How do I template a function typedef using an alias declaration?
I'm simply trying to convert my current typedef:
typedef void (Foo::*CallbackName)(int arg);
Into a function alias, which I have looking like:
template
using T_CallbackName = void(T::*CallbackName)(int arg);
Is this correct? Alias…
Danny
- 354
- 3
- 13
1
vote
1 answer
Why does std::add_lvalue_reference not behave as expected?
#include
template
using Ref1 = T & ;
template
using Ref2 = std::add_lvalue_reference_t;
template
void f1(Ref1)
{}
template
void f2(Ref2)
{}
int main()
{
int n{};
…
xmllmx
- 39,765
- 26
- 162
- 323
1
vote
4 answers
Declaring using statement after namespace declaration
I am writing a utility library which is made up of several "Packages". The classes in each package are contained in various namespaces. I have an idea as to how I can simplify the situation by automatically declaring using statements at the end of…
Dave
- 7,283
- 12
- 55
- 101
1
vote
3 answers
namespace composition and selection
After reading The C++ Programming Language 4th edition (section 14.4.4 -
Composition and Selection) I thought that the following program would compile correctly:
#include
namespace foo {
int var = 0;
// more…
carlo
- 325
- 1
- 4
- 12
1
vote
2 answers
Why is the move constructor not inhereted by using declaration
In the following code the move constructor of the derived class is obviously not generated although the base class is move constructible.
#include
#include
#include
#include
template
class…
Marcel
- 1,688
- 1
- 14
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1
vote
0 answers
Policy class with template alias
I am not sure whether the question title is right.
I am looking for a method to choose one of the template specializations of class A based on template alias from policy class.
Is there any way to achieve this ?
// g++ -Wall -std=c++11 p.cpp…
tadtm
- 53
- 6
1
vote
2 answers
Using-declaration to move name to another namespace?
Given:
namespace One {
void foo(int x) {
munch(x + 1);
}
};
namespace Two {
// ... see later
}
...
void somewhere() {
using namespace Two;
foo(42);
...
is there any difference between the following two variants:
a)
namespace Two…
Martin Ba
- 37,187
- 33
- 183
- 337
1
vote
1 answer
Example of error caused by using directive in namespaces
I'm trying to understand what kind of errors could arise from including using declarations in namespaces. I'm taking into account these links.
I'm trying to create an example where an error is being caused by a name being silently replaced by an…
swahnee
- 2,661
- 2
- 24
- 34
1
vote
0 answers
Use of Elaborated Type Specifier to create object of hidden class
I have following code snippet :
namespace A {
class X {
X()
{
std::cout<< " I am here in Constructor";
}
};
}
namespace B
{
void X(int)
{
…
logic seeker
- 95
- 9
1
vote
0 answers
Is there a work-around for parameter pack expansion in using declarations
Parameter pack expansion in using declarations is not supported in C++14, and so the following code fails to compile:
template struct A
{
virtual void foo(T);
};
template struct B: public A...
{
using…
Jens
- 9,058
- 2
- 26
- 43
1
vote
0 answers
Visual Studio 2015 bug? Ambiguous member function access, order of ancestor classes overrides using statement
Am I missing something, or did I find a Visual Studio bug?
Bugs aside, is using this type of inheritance OK or evil?
GCC 4.9.0 produces my expected results:
base.getProperty() 1
otherBase.getProperty() 2
derivedA.getProperty()…
user1902689
- 1,655
- 2
- 22
- 33
1
vote
0 answers
Using redeclaration within a block scope
Here is the code which causes a compile-time error:
#include
int a;
void f()
{
using ::a;
using ::a; //'a' is already declared in this scope.
}
int main(){ }
DEMO
What the standard says is (N4296::7.3.3/10…
user2953119
1
vote
1 answer
Calling an aliased-declared base class constructor in a different namespace
I am trying to understand some details of alias-declared classes through C++11's using and how/why this affects a base class constructor call.
Example Code
#include
namespace N {
template
struct Foo
{
// Foo(){};…
hcc23
- 1,180
- 11
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1
vote
1 answer
include and using declaration
using ::bb::cascades::Application;
#include
What do these two declaration mean?
And are there any good tutorials which states the using directive/declaration deeply?Thanks.
Tahlil
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