Since template metafunctions execute at compile time, their results can be used in contexts that require compiletime values. There have been some articles dealing with template metaprogramming before over here. Algorithms are expressed using template recursion as a looping construct and class template specialization as a conditional construct. This technique is called template metaprogramming tmp. 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. The rest of this guide uses the term alias to mean alias template. Most people insist on trying to metaprogram from inside their favorite language. We can get rid of all of the manual method calls and simply list the genres in an array.
It seems really cool, make the compiler do most of the work. The complete guide since it is also the definitive reference for templates in general. Template metaprogramming has most of the restrictions of a functional programming language, so recursion is the primary looping construct. Weve had the idea of writing about template metaprogramming for. A complete reference manual for the mpl components, also to be included with the boost distribution. Well include a release of boost with an uptodate mpl implementation. Metaprogramming with templates yes, the code checks whether the number is a prime number template struct isprime2. Template metaprograms consist of class templates operating on numbers andor types as data. The use of templates can be thought of as compiletime polymorphism. In some cases, this can be used to optimize the eventual runtime of a program. 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. Pdf c templates the complete guide pdf book manual.
Template metaprogramming techniques for conceptbased. That doesnt work if the language doesnt support metaprogramming well. 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. But if we look again at the manual approach, we can see a certain. This is basically thorough documentation for the boost mpl. The if template was the rst control structure in a generic form 3 and the remaining control structures were published in 4. Need help mixing computed goto and loop unrolling via template metaprogramming.
Keep talking and nobody explodes is now available on ios and android. It can, for the most part, be considered to be programming with types in that, largely, the. I have very simple program that uses tmp,it calculates the square of a number, but it doesnt seem to. A metaprogram is a program that generates or manipulates program code. After an introduction to template metaprogramming and presenting the. Things like template, which look really weird but behave in an even more bizarre way. So, in metaprogramming, we create code that will run when the code is compiled. Mos 4465a is an advanced financial ac modern advanced accounting in canada, 8th edition, mcgraw. The purpose of the system is to support the algorithmic construction of programs at compiletime.
Even while its fairly obvious that the executable will print something, its still great. This allows computations to be performed once at compile time rather than at each run time. The output of these templates include compiletime constants, data structures, and complete functions. Concepts, tools, and techniques from boost and beyond by david abrahams and aleksey gurtovoy. Copyright c 20, decorators with args 47 from functools import wraps def debugprefix. Practical techniques for building better software, philip romanik and.
For simplicity reasons, i only provide a screenshot of the main program and the corresponding assembler instructions. The ability to generate code at compile time allows the programmer to implement such features as polytypic programs, macrolike expansion, user directed optimization such. The introduction to template metaprogramming in the guidelines ends. Techniques for making the mpl work on vc6vc7borlandgcc2.
Metaprogramming allows programs to create methods on the fly instead of having to define them in the program itself. Concepts, tools, and techniques from boost and beyond david abrahams, aleksey gurtovoy. We propose a new extension to the purely functional programming language haskell that supports compiletime metaprogramming. Concepts, tools, and techniques from boost and beyond.
A way around this is to do metaprogramming from outside the language, using program transformation tools. Otherwise the user will face a horrible compiler error saying something along the lines of. This post starts a series of articles following the contrived and tortuous path down insanity lane. The rst article on template metaprogramming 7 was published in 1995. Metaprogramming or more specifically, template metaprogramming is the practice of using templates to create constants, functions, or data structures at compiletime. Template metaprogramming for haskell microsoft research.
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