Questions tagged [explicit-specialization]
71 questions
62
votes
1 answer
What can and can't I specialize in the std namespace?
Users are allowed to add explicit specializations to the std namespace. However, there are a few templates that I am explicitly forbidden from specializing.
What templates can and can't I specialize?
R. Martinho Fernandes
- 228,013
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18
votes
2 answers
Is there provision specifying the restriction on "return type" in a function template explicit specialization?
template
void fun(T){}
template<>
int fun(int){return 0;}
Consider this example, it is rejected by all implementations. However, I haven't found any persuasive provision in the current standard that specifies this explicit specialization…
xmh0511
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16
votes
1 answer
How to properly use GHC's SPECIALIZE pragma? (Example: specializing pure function from monadic ones using Identity.)
As an example, suppose I want to write a monadic and non-monadic map over lists. I'll start with the monadic one:
import Control.Monad
import Control.Monad.Identity
mapM' :: (Monad m) => (a -> m b) -> ([a] -> m [b])
mapM' _ [] = return []
mapM' f…
Petr
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14
votes
5 answers
Difference between explicit specialization and regular functions when overloading a template function
I'm on a roll today. Here goes n00b question number 7:
What's the difference between explicit specialization and just regular functions when you try to overload a template function?
What's the appropriate situation to use the explicit…
Pwnna
- 9,178
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12
votes
1 answer
Explicit specialization of member function template in source file
I have a class with a member template function:
// writer.h
class Writer {
public:
...
template
void addField(const std::string& name, V v)
{
// write something
}
};
And in Writer's source file,…
Barry
- 286,269
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12
votes
1 answer
class template state data member, not an entity that can be explicitly specialized
I got an error in the code below:
template::value>
class class_name;
template<>
class class_name{
public:
static string const value;
};
template<>
string const class_name
user955249
12
votes
2 answers
Array type deduction in a function template
I have a template method as follows:-
template
void ProcessArray(T array[length]) { ... }
And then I have code using the above method:-
int numbers[10] = { ... };
ProcessArray(numbers);
My question is why do I have…
Higher-Kinded Type
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11
votes
2 answers
Can a class template explicit specialization also declare something else?
It would be nice if this code were invalid. But it's conceptually sound, and GCC accepts it although Comeau doesn't:
template< typename > struct t;
template<> struct t< int > {} r; // Bad declarator! Don't pee on the carpet!
(Edit: the above…
Potatoswatter
- 134,909
- 25
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10
votes
1 answer
Template static definition and explicit specialization instantiation errors in MSVC
I'm wondering why the following code runs just fine in gcc
#include
using namespace std;
template
struct F {
static T const value;
};
template<>
struct F { // Specialization
static int const value;
};…
Marco A.
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9
votes
1 answer
Nested class explicit specilization: different compiler behavior
The following code compiles fine with clang++ 6.0.0 and g++ 7.3.0 (compilation flags are -std=c++14 -Wall -Wextra -Werror -pedantic-errors) but fails to compile with vc++ 19.10.25017 (compilation flag is /Za):
template
struct A
{
…
Constructor
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9
votes
6 answers
Selecting an explicit specialization of a class based on a derived type
Hi I'm having problems selecting the correct version of a templated class which has an explicit specialization. I'm wanting to select a specialization using a derived class of the class used to specialize. The scenario is:
#include…
user176168
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8
votes
1 answer
An explicit specialization cannot be a friend declaration
The code
template
void foo(const T& t)
{}
template
class A
{
template <>
friend void foo(const T& t)
{}
};
gives compile error
"defining explicit specialization ‘foo’ in friend declaration friend void…
Vahagn Babajanyan
- 379
- 2
- 12
8
votes
1 answer
SFINAE: detect existence of a template function that requires explicit specialization
As a follow-up to my previous question, I am trying to detect the existence of a template function that requires explicit specialization.
My current working code detects non-template functions (thanks to DyP's help), provided they take at least one…
syam
- 14,701
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7
votes
3 answers
Why is this C++ explicit template specialization code illegal?
(Note: I know how it is illegal, I'm looking for the reason that the language make it so.)
template void Foo(); // Note: no generic version, here or anywhere.
int main(){
Foo();
return 0;
}
template<> void…
BCS
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7
votes
2 answers
explicit specialization of class method - symbol already defined
The One Definition Rule states that a program should contain one definition of every non-inline function. For members of template classes, this not entirely clear to me:
///////////
// Tfoo.h
template class A {
void foo(){}
…
xtofl
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