Its aim is to teach c to a beginner, but with enough of the details so as not be outgrown as the years go by. For the love of physics walter lewin may 16, 2011 duration. A class template is instantiated by passing a given set of types to it as template arguments. 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. Your price below reflects our everyday 20% off savings. What weve done now is program a little function or subroutine that is evaluated compiletime, using tmp.
Jun 21, 2015 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. Template metaprogramming is generally not used in practical programs, it is an interesting conecpt though. Metaprogramming with templates yes, the code checks whether the number is a prime number template struct isprime2. Mos 4465a is an advanced financial ac gold advanced maximiser with key. I have very simple program that uses tmp,it calculates the square of a number, but it doesnt seem to.
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. When c was developed, maths libraries implemented functions. This post starts a series of articles following the contrived and tortuous path down insanity lane. We can all learn enough to use it in our daytoday coding. The two most widely used textual macro systems are the c preprocessor and the m4 macro processor. Concepts, tools, and techniques from boost and beyond pdf,, download ebookee alternative practical tips for a improve ebook reading. Plus there are some things that could be done with staticif that cannot be done currently with templates due to the intricacies of how it works or they could just relax some of the. I was motivated to write this after i read eric nieblers thoughtprovoking tiny metaprogramming library article.
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. These pioneers greatly influenced the field, and basically what should be written is now written. Oct 20, 2005 the c preprocessor cpp first lets look at metaprogramming that involves textual macro languages. It was not designed to be a first order language, so the syntax is very cumbersome 2. A template parameter is a special kind of parameter. The basics template metaprogramming tmp arose by accident. Grab it directly from the iterator c deref, parent, visitcount grab the first value from the subtree contained in the iterator c deref. Lets explore template metaprogrammingwith a couple of code. C is ideally suited to modern computers and modern programming.
It allows even inexperienced programmers to perform compiletime computations without doing any tmp on the surface. 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 ability to generate code at compile time allows the programmer to implement such features as polytypic programs, macrolike expansion, user directed optimization such. The output of these templates include compiletime constants, data structures, and complete functions. Weve had the idea of writing about template metaprogramming for. I have a lot of convoluted template code with sfinae and specialization that is awful to read and write. The rst article on template metaprogramming 7 was published in 1995. Therefore, i call this projecttechnique template metaprogramming programming. An introduction to metaprogramming for scientific computing dr conrad sanderson senior research scientist version 1. The ability to generate code at compile time allows the programmer to implement such features as polytypic programs, macrolike.
For example, a software company may need sort for different data types. The if template was the rst control structure in a generic form 3 and the remaining control structures were published in 4. Metaprogramming or more specifically, template metaprogramming is the practice of using templates to create constants, functions, or data structures at compiletime. Parsing, compiling, and static metaprogramming jsconf eu 20 duration. Most people insist on trying to metaprogram from inside their favorite language. Caveat i decided to do this talk after getting thoroughly lost on the recent talk on sfinae. A way around this is to do metaprogramming from outside the language, using program transformation tools. Things like template, which look really weird but behave in an even more bizarre way. Rather than writing and maintaining the multiple codes, we can write one sort and.
With variadic templates, parameter packs and template aliases. May 26, 2016 its no more difficult conceptually than haskell or some other first order language. Hana libraries, and functional reactive programming with the rxcpp. Function templates are special functions that can operate with generic types. We propose a new extension to the purely functional programming language haskell that supports compiletime metaprogramming.
The latter form was introduced to avoid confusion, since a type parameter need not be a class. Both expressions have the same meaning and behave in exactly the same way. Template metaprogramming for haskell microsoft research. Unrolling and simplifying expressions with template haskell, by.
Template metaprogramming is turingcomplete, meaning that any computation expressible by a computer program can be computed, in some form, by a template metaprogram. So, in metaprogramming, we create code that will run when the code is compiled. The purpose of the system is to support the algorithmic construction of programs at compiletime. Most ebooks are available as drmfree epub, mobi, and pdfall together for one price so you can learn on your desktop or preferred device.
A macro is a piece of code that executes at compile time and either performs textual manipulation of code tobe compiled e. And inspiring introduction to template metaprogramming. There have been some articles dealing with template metaprogramming before over here. This allows us to create a function template whose functionality can be adapted to more than one type or class without repeating the entire code for each type. It seems really cool, make the compiler do most of the work. The simple idea is to pass data type as a parameter so that we dont need to write the same code for different data types. Template metaprogramming is a generic programming technique that uses extremely early binding. C deref this specialization is only for leaf nodes. Lets explore template metaprogrammingwith a couple of code examples. This allows computations to be performed once at compile time rather than at each run time. Your contribution will go a long way in helping us serve. Sep 09, 20 in some cases, this can be used to optimize the eventual runtime of a program. Template metaprogramming for haskell, by tim sheard and simon peyton jones, oct 2002.
An introduction to template metaprogramming barney dellar software team lead toshiba medical visualisation systems. Concepts, tools, and techniques from boost and beyond book. Technically metaprogramming is code that writes code. The addition of staticif would make it much cleaner. 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. The compiler acts as an interpreter or a virtual computer that emits the instructions that make up the final program. Tmp doesnt have branching, so we use specialization. Its no more difficult conceptually than haskell or some other first order language. Metaprogramming with templates yes, the code checks whether the number is a prime number template jun 11, 2015 for the love of physics walter lewin may 16, 2011 duration. That doesnt work if the language doesnt support metaprogramming well. This technique is called template metaprogramming tmp.