What are the important considerations when using C++ function templates?

When using C++ function templates, there are several things to keep in mind:

1. Definition and declaration of function templates are typically placed in a header file for sharing across multiple source files. Additionally, the definition and declaration of function templates must also adhere to the syntax and naming conventions of C++.
2. Type deduction for actual parameters: Function templates can automatically deduce the types of template parameters based on the types of actual parameters. Therefore, when calling a function template, it is necessary to ensure that a clear template parameter type can be deduced. If a clear type cannot be deduced, the issue can be resolved by explicitly specifying the template parameters.
3. Function template specialization: Sometimes, it is necessary to provide a customized template implementation for specific types. This can be achieved using function template specialization. It is important to note that function template specialization must meet certain conditions and syntax rules.
4. Restrictions on template parameters: Function templates can restrict template parameters to ensure only types that meet specific conditions can be used. This can be achieved through type constraints or static assertions for limiting template parameters.
5. Function template overloading: When there are multiple function templates with the same or partially same template parameters, it is important to ensure that their actual arguments can be clearly distinguished. Otherwise, it may result in conflicts with function template overloading.
6. The deduction order of template arguments: In specific cases, the deduction order of template arguments may be different from the order of function parameters. This could result in incorrect deduction results, so it is important to adjust the order of template parameters or use explicitly specified template parameters to resolve the issue.
7. Implicit instantiation: Function templates are typically implicitly instantiated when used. Therefore, it is important to ensure that the implementation of function templates is correct in all possible instantiation scenarios.
8. Symbolic link issue: If the definition and declaration of a function template are in different source files, it may result in symbolic link issues. This problem can be resolved by using explicit instantiation of the template or by placing the definition of the function template directly in the header file.

In general, understanding the syntax rules and characteristics of C++ function templates, as well as being mindful of the points mentioned above, is necessary to ensure the correct use and instantiation of function templates.