Concepts, tools, and techniques from boost and beyond. This is basically thorough documentation for the boost mpl. It can, for the most part, be considered to be programming with types in that, largely, the. We can get rid of all of the manual method calls and simply list the genres in an array. This post starts a series of articles following the contrived and tortuous path down insanity lane.
Techniques for making the mpl work on vc6vc7borlandgcc2. These pioneers greatly influenced the field, and basically what should be written is now written. This allows computations to be performed once at compile time rather than at each run time. Template metaprograms consist of class templates operating on numbers andor types as data. Metaprogramming or more specifically, template metaprogramming is the practice of using templates to create constants, functions, or data structures at compiletime. Algorithms are expressed using template recursion as a looping construct and class template specialization as a conditional construct. Even while its fairly obvious that the executable will print something, its still great. We propose a new extension to the purely functional programming language haskell that supports compiletime metaprogramming. The rest of this guide uses the term alias to mean alias template. Weve had the idea of writing about template metaprogramming for. After an introduction to template metaprogramming and presenting the. Template metaprogramming has most of the restrictions of a functional programming language, so recursion is the primary looping construct. Most people insist on trying to metaprogram from inside their favorite language.
Metaprogramming with templates yes, the code checks whether the number is a prime number template struct isprime2. A complete reference manual for the mpl components, also to be included with the boost distribution. The complete guide since it is also the definitive reference for templates in general. Well include a release of boost with an uptodate mpl implementation. Template metaprogramming techniques for conceptbased. Template metaprogramming tmp is a metaprogramming technique in which templates are used by a compiler to generate temporary source code, which is merged by the compiler with the rest of the source code and then compiled. Practical techniques for building better software, philip romanik and. So far weve learned the basic constructs of template metaprogramming loops, branching, return values and some basic list operations getting the length of a list, appending and prepending elements, checking if an element is included in a list. Concepts, tools, and techniques from boost and beyond by david abrahams and aleksey gurtovoy. Metaprogramming allows programs to create methods on the fly instead of having to define them in the program itself. Template metaprogramming for haskell microsoft research. I have very simple program that uses tmp,it calculates the square of a number, but it doesnt seem to. So, in metaprogramming, we create code that will run when the code is compiled.
The introduction to template metaprogramming in the guidelines ends. Template metaprograms can generate useful code when interpreted by the compiler, such as a massively inlined algorithm that is, an implementation of an algorithm which works for a specific input size, and has its loops unrolled. There have been some articles dealing with template metaprogramming before over here. Otherwise the user will face a horrible compiler error saying something along the lines of. It seems really cool, make the compiler do most of the work.
The rst article on template metaprogramming 7 was published in 1995. Template metaprograms are often hard to comprehend, and i must warn you that this may well apply to many of the codeblocks in this article. That doesnt work if the language doesnt support metaprogramming well. The ability to generate code at compile time allows the programmer to implement such features as polytypic programs, macrolike expansion, user directed optimization such.
Need help mixing computed goto and loop unrolling via template metaprogramming. In some cases, this can be used to optimize the eventual runtime of a program. The purpose of the system is to support the algorithmic construction of programs at compiletime. Concepts, tools, and techniques from boost and beyond david abrahams, aleksey gurtovoy. Mos 4465a is an advanced financial ac modern advanced accounting in canada, 8th edition, mcgraw.
A complete guide to programming in c peter prinz, ulla kirchprinz. A way around this is to do metaprogramming from outside the language, using program transformation tools. Copyright c 20, decorators with args 47 from functools import wraps def debugprefix. But if we look again at the manual approach, we can see a certain. Since template metafunctions execute at compile time, their results can be used in contexts that require compiletime values. The output of these templates include compiletime constants, data structures, and complete functions.