The library brings together important abstractions from the generic and functional programming worlds to build a powerful and easytouse toolset which makes template metaprogramming practical enough. Metaprogramming is a programming technique in which computer programs have the ability to treat other programs as their data. Mos 4465a is an advanced financial ac gold advanced maximiser with key. First was the c preprocessor kr88 whose macros allow generating code. Template metaprogramming allows the programmer to focus on architecture and delegate to the compiler the generation of any implementation required by client code. Despite the existence of numerous real systems built with template. I have very simple program that uses tmp,it calculates the square of a number, but it doesnt seem to. In programming, one of the most important elements that we rely on is the availability of containers, and data structures such as. All of the code in the presentation is in this repository. Things like template, which look really weird but behave in an even more bizarre way. Pdf template metaprogramming is an emerging new direction of generative. Its practicing is complex, involving development demands similar to any actual system.
Pdf c template metaprogramming download full pdf book. A complete mpl reference manual, in html and pdf form. The book deals with language aspects, design patterns, examples and applications. Template metaprogramming can be used to automatically produce the right type.
Template metaprogramming is a great technique when used correctly. Template metaprogramming is in fact turingcomplete, meaning that any computation expressible by a computer program can be computed, in some form, by a template metaprogram. Each instance of a template generates code for the actual. An introduction to template metaprogramming barney dellar software team lead toshiba medical visualisation systems. With variadic templates, parameter packs and template aliases. Template metaprogramming map metainformation metafunctions membre traits traits classes traits templates lists and trees as nested templates computing numbers fibonacci control structures computing types if,switch, while,do,for computing code ewhile,edo, efor expression templates 15. Things like template int n, which look really weird but behave in an even more bizarre way. Jun 11, 2015 template metaprogramming john edwards of thatgamecompany digipen game engine architecture club. Pdf c template metaprogramming download ebook for free. The ability to generate code at compile time allows the programmer to implement such features as polytypic programs, macrolike expansion, user directed optimization such. Posts about template metaprogramming written by crazy eddie. Each instance of a template generates code for the actual types used. Template metaprogramming is something that originated by accident, as a side effect of the original template mechanism, which was intended as a way to allow writing small generic functions.
Template metaprogramming is the practice of using templates to generate types and functions to perform computations at compiletime and generate programs. In the previous diagram we show the different names for the elements. Reflection support by means of template metaprogramming pdf. Hana libraries, and functional reactive programming with the rxcpp. Jun 21, 2015 essentially, metaprogramming is writing code that writes code hence the meta part. The first metaprogram history is just on damn thing after another nicolas cage. If n items are put into m containers, with n m, then at least one container must contain more than one item. Template metaprogramming tmp is a metaprogramming technique in which templates are. Template metaprogramming is generally not used in practical programs, it is an. There have been some articles dealing with template metaprogramming before over here. Therefore, i call this projecttechnique template metaprogramming programming.
Starting off the list for examples of metaprogramming is monkey patching. The two newer necessities arent used in the code in order that the examples might be rich, illustrate the aim, and be run with confidence. When we write code it usually looks the same for many different functions. It means that a program can be designed to read, generate, analyze or transform other programs, and even modify itself while running. The actual value of t can be deduced by the compiler for function calls. Code is generated each time the template is invoked with an actual value for t. How to create gui in c programming using gtk toolkit. This is very obvious if we write an algorithm to sort a list of data, depending upon the data type we would need a different implementation of essentially the same thing. We propose a new extension to the purely functional programming language haskell that supports compiletime metaprogramming. This post starts a series of articles following the contrived and tortuous path down insanity lane. Sep 09, 20 what weve done now is program a little function or subroutine that is evaluated compiletime, using tmp. Ranges are just slow to compile one of the reasons is that eric niebler emulated concepts everywhere using existing metaprogramming facilities actual concepts in the language may help, but as they are now experimentally implemented in gcc, they are reported to be slow yet, another is that lazy evaluation. It lets you write programs that you can get the compiler to execute at compile time. An introduction to meta programming for scientific computing dr conrad sanderson senior research scientist version 1.
A macro is a piece of code that executes at compile time and either performs. In fact many template implementations implement flow control only through recursion, as seen in the example below. The two newer standards are not used in the code so that the examples can be rich. The output of these templates include compiletime constants, data structures, and complete functions. Reflection support by means of template metaprogramming.
The best way to think of a template is to do something similar to what the compiler does. 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. Youre thinking, hes done with his pass through the stl, hes written about traits and policies, now he needs to write about more topics in generic programming in general, and he cant think of anything that a real software engineer would be interested in. Programming languages computer programming computer technology computer science computer coding learn to code deep learning data science machine learning. Im not an expert in any kind of compile time computing methods but i know that template metaprogramming provides such a functionality. In it, the actual call to the script function is performed and the return value of it given back to the caller. It allows even inexperienced programmers to perform compiletime computations without doing any tmp on the surface. The basics because tmp was not designed, the syntax is unpleasant and. The library brings together important abstractions from the generic and functional programming worlds to build a powerful and easytouse toolset which makes template metaprogramming practical enough for the realworld. A variable template is exactly 100% equivalent to a static data member of a.
Yes, its a weird name, but its a powerful and dangerous tool. In that case, it is useful to preevaluate the code with respect to the constant. Tmp is a bit esoteric many software companies do not allow it however, there are some users boost. Thus, template metaprogramming can accomplish truly generic code, facilitating code minimization and better maintainability citation needed. Other readers will always be interested in your opinion of the books youve read. The ability to generate code at compile time allows the programmer to implement such features as polytypic programs, macrolike. On the other hand it might result in code bloat and performance decrease. A metaprogram is a program that generates or manipulates program code. 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. Template metaprogramming often makes use of compiletime computations, whether via templates or constexpr functions.
We propose a new extension to the purely functional programming language haskell that supports compiletime meta programming. The pigeonhole principle is one of the most obvious fundamentals in mathematics. While i consider myself falling rather in the camp of the aficionados, ive met a lot more people that dont have a strong interest for it, or that even find it downright disgusting, than tmp enthusiasts. The introduction to template metaprogramming in the guidelines ends uniquely.
Template metaprogramming template metaprogramming is a turing complete language every intuitive computable number can be computed meaning. It seems really cool, make the compiler do most of the work. The two newer standards are not used in the code so that the examples can be rich, illustrate the point, and be run with confidence. Template metaprogramming for haskell microsoft research. The boost template metaprogramming library is a very powerful library but there are some things that become necessary that can make things really tough to read. Template metaprogramming is both a curiosity and a powerful optimisation method. During this introduction to programming at compile time, i explicitly write about. With the help of cleverly dened templates the programmer. But most of the time, template metaprogramming is used and useful in small, isolated cases, basically to smooth out bumps and exceptional cases, to make a set of types look and behave uniformly, allowing you to use generic programming more efficiently. Another advantage is that you can look at a template class and immediately see if it is a template metaprogram or an ordinary template class. In this hybrid approach, source code contains two programs. Looking at the actual code it seems natural for the programmer to define double as. So, using templates, we can write programs that do computation at compile time, such programs are called template metaprograms. And inspiring introduction to template metaprogramming.
The book deals with language aspects, design patterns, examples and applications seen as case studies. An introduction to metaprogramming for scientific computing dr conrad sanderson senior research scientist version 1. I was motivated to write this after i read eric nieblers thoughtprovoking tiny metaprogramming library article. Heres a basic example showing how to get the compiler to calculate the greatest common divisor of two numbers. Template metaprogramming is generally not used in practical programs, it is an interesting conecpt though. The purpose of the system is to support the algorithmic construction of programs at compiletime. Outside of the lisp family, c and its preprocessor became a tool of. What weve done now is program a little function or subroutine that is evaluated compiletime, using tmp. It is so obvious that you may be surprised that there is even a name for it. In this paper we aim to give some insight on one of the uses of template programming, which is template metaprogramming, a technique whereby the compiler acts as an interpreter. Download object oriented programming book by robert loafer pdf. Template metaprogramming is an emerging new direction. Template metaprogramming is generally not used in practical programs, it is an interesting conecpt.
Monkey patching is an object oriented programming technique that allows developers to. Template metaprograms have no mutable variables that is, no variable can change value once it has been initialized, therefore template metaprogramming can be seen as a form of functional programming. In general, macros are frowned upon in this role and templates are preferred, although they are not as generic. This post starts a series of articles following the contrived and tortuous path down insanity lane and into the mouth of the.