Parameterized constraints
There are two kinds of parameterized constraints, one to check if an expression between two operands are allowed, and one for checking a constant value. It’s not legal to put a constraint on non-constant values.
Concepts
Exception constraints
Exception constraints check if an expression E is marked noexcept, and returns true only if it evaluates to noexcept(true).
Argument deduction constraints
Argument deduction constraints are similar to implicit conversion constraints, except argument deduction constraints have one or more placeholders in the trailing return type field.
Type and implicit conversion constraints
Type constraints
Type constraints restrict by limiting the type accepted. By this you can only accept types, which contain some properties or a set of subtypes.
Predicate and expression constraints
Predicate constraints
Predicate constraints checks the expression if it matches a criteria.
Conjunctions and Disjunctions
A conjunction is a word used to connect clauses or sentences or to coordinate words in the same clause.
The nine types of constraints
With Concepts Lite there are nine types of constraints. Each serves a different purpose, and those nine types of constraints are:
Function and variable concepts
In general, there are two kinds of distinct concepts. Those are function concepts and variable concepts. They are similar to their non-concept siblings template functions and template variables. If you haven’t heard about template variables, you’re not alone. Those are new in C++14, and allows you to define a variable as a template. However, variable concepts are modeled around template variables, so they will be covered.
Getting started with arithmetic concepts
Not long ago, I implemented a Matrix class with template expressions. Sadly, I cannot release it to the public because it belongs to my employer. Such libraries dealing with arithmetic will benefit greatly from concepts. The compile errors from not implemented operators are horrendous.
Your own concepts
The easiest concept is probably the boolean concepts true and false.
