C++ template specialization

This tutorial will give the idea of the template specialization, but will be limited to just the basic. In other words, a template is a mechanism that allows a programmer to use types as parameters for c++ template specialization class or a function.

Explicit specialization may be declared in any scope where its primary template may be defined which may be different from the scope where the primary template is defined; such as with out-of-class specialization of a member template. Explicit specialization has to appear after the non-specialized template declaration. Specialization must be declared before the first use that would cause implicit instantiation, in every translation unit where such use occurs:. A template specialization that was declared but not defined can be used just like any other incomplete type e. When specializing a function template, its template arguments can be omitted if template argument deduction can provide them from the function arguments:. A function with the same name and the same argument list as a specialization is not a specialization see template overloading in function template. Default function arguments cannot be specified in explicit specializations of function templates, member function templates, and member functions of class templates when the class is implicitly instantiated.

C++ template specialization

Partial specialization may be declared in any scope where its primary template may be defined which may be different from the scope where the primary template is defined; such as with out-of-class specialization of a member template. Partial specialization has to appear after the non-specialized template declaration. The following restrictions apply to the argument-list of a partial template specialization:. Partial template specializations are not found by name lookup. Only if the primary template is found by name lookup, its partial specializations are considered. In particular, a using declaration that makes a primary template visible, makes partial specializations visible as well:. Informally "A is more specialized than B" means "A accepts a subset of the types that B accepts". Formally, to establish more-specialized-than relationship between partial specializations, each is first converted to a fictitious function template as follows:. The function templates are then ranked as if for function template overloading. The template parameter list and the template argument list of a member of a partial specialization must match the parameter list and the argument list of the partial specialization. Just like with members of primary templates, they only need to be defined if used in the program. Explicit full specialization of a member of a partial specialization is declared the same way as an explicit specialization of the primary template. If a primary template is a member of another class template, its partial specializations are members of the enclosing class template. If the enclosing template is instantiated, the declaration of each member partial specialization is instantiated as well the same way declarations, but not definitions, of all other members of a template are instantiated. If the primary member template is explicitly fully specialized for a given implicit specialization of the enclosing class template, the partial specializations of the member template are ignored for this specialization of the enclosing class template.

Member access operators. Similar Reads. Class member templates.

How to begin Get the book. Practice problems Quizzes. Template Specialization and Partial Template Specialization By Alex Allain Template Specialization In many cases when working with templates, you'll write one generic version for all possible data types and leave it at that--every vector may be implemented in exactly the same way. The idea of template specialization is to override the default template implementation to handle a particular type in a different way. For instance, while most vectors might be implemented as arrays of the given type, you might decide to save some memory and implement vectors of bools as a vector of integers with each bit corresponding to one entry in the vector. So you might have two separate vector classes.

How to begin Get the book. Practice problems Quizzes. Template Specialization and Partial Template Specialization By Alex Allain Template Specialization In many cases when working with templates, you'll write one generic version for all possible data types and leave it at that--every vector may be implemented in exactly the same way. The idea of template specialization is to override the default template implementation to handle a particular type in a different way. For instance, while most vectors might be implemented as arrays of the given type, you might decide to save some memory and implement vectors of bools as a vector of integers with each bit corresponding to one entry in the vector. So you might have two separate vector classes.

C++ template specialization

Templates are parameterized by one or more template parameters , of three kinds: type template parameters, non-type template parameters, and template template parameters. When a class template specialization is referenced in context that requires a complete object type, or when a function template specialization is referenced in context that requires a function definition to exist, the template is instantiated the code for it is actually compiled , unless the template was already explicitly specialized or explicitly instantiated. Instantiation of a class template does not instantiate any of its member functions unless they are also used. At link time, identical instantiations generated by different translation units are merged. The definition of a class template must be visible at the point of implicit instantiation, which is why template libraries typically provide all template definitions in the headers e. Files that instantiated exported templates did not need to include their definitions: the declaration was sufficient. Implementations of export were rare and disagreed with each other on details. A simple-template-id that names a class template specialization names a class.

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Campus Experiences. Order of evaluation. Elaborated type specifier. Improve Improve. Parameters and arguments. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Interview Experiences. Potentially-evaluated expressions. Function template. In particular, a using declaration that makes a primary template visible, makes partial specializations visible as well:. Template allows us to define generic classes and generic functions and thus provide support for generic programming. Inline assembly. Article Tags :. Template argument deduction.

Explicit specialization may be declared in any scope where its primary template may be defined which may be different from the scope where the primary template is defined; such as with out-of-class specialization of a member template. Explicit specialization has to appear after the non-specialized template declaration. Specialization must be declared before the first use that would cause implicit instantiation, in every translation unit where such use occurs:.

The most specialized specialization is used, if it is unique if it is not unique, the program cannot be compiled. Only if the primary template is found by name lookup, its partial specializations are considered. Keywords Escape sequences. Copy constructor. But when the user feeds characters into the parameter, the meaning is not obvious. Hire With Us. Additional resources In this article. Operator precedence. An Example Program for class template specialization In the following program, a specialized version of class Test is written for int data type. What we want to do here is use a partial specialization based on whether the type is a pointer or a non-pointer you could get fancy and have multiple levels of pointers, but we'll stay simple. The second thing to note is that T is now the type pointed to; it is not itself a pointer. Submit your entries in Dev Scripter today. But we need to look at syntax carefully. Trending in News. Open In App.