Questions tagged [template-meta-programming]
For code that uses templates to generate compile-time executed code. For ordinary use of templates, use the 'template' tag instead.
272
questions
3
votes
1
answer
63
views
C++ printing library with templates
I was mad C++ did not have support for printing containers. I also could not find a header only library for printing containers so I decided to make my own. My goals were: 1) practicing templates 2) ...
- 105
3
votes
1
answer
85
views
Partial specialization of class template with minimal code duplication
I have a class template that stores an std::optional<T>. A very reduced version of the class template looks like this:
...
- 133
1
vote
1
answer
51
views
Template for making distinct numeric type aliases
I've tried to make a small template for the creation of distinct (incompatible) numerical types. For example both row and column indices are usually represented as the same underlying type. However it ...
- 77
3
votes
1
answer
470
views
C++ enum to string conversion utility
I needed to find a way to convert a bunch of enums to string for displaying in C++. The two main ways I found when searching was using dark magic macros or voodoo magic template metaprogramming.
As I ...
- 75
4
votes
0
answers
48
views
Variadic pack class providing operations over types without constructing objects of those types
Sometimes I find I want to call a function passing each of a set of types as a template parameter, but without needing to construct an object of those types. I also may want to do this in multiple ...
- 243
4
votes
2
answers
152
views
Transpose types variadicly
I want to do template metaprogramming to compute the conversion from std::variant<Ts...> to ...
- 143
3
votes
1
answer
74
views
scoped timer class (3rd revision)
Again, here is the previous question. I have (re)revised my custom scoped timer using the valuable feedback I got from a helpful member of this community. However I feel the need to ask this question ...
- 635
-2
votes
2
answers
73
views
Is there a more elegant solution to store and process different types using templates? [closed]
I'm trying to create some system for profiling and I need to track different data types (double, float int). I have a container that can hold some base type, and then perform actions on the concrete ...
- 99
4
votes
1
answer
1k
views
Template to unpack arguments to a std::function
I am writing some C++ code to interact with an external scripting language. I want to be able to register arbitrary C++ callable code as functions to be called from the script.
The scripting library ...
- 161
3
votes
1
answer
363
views
C++: Visit Any Type Holding Other Types (`std::any`, `std::variant`, etc.)
Intro
I want to visit the value held by a class, which could be of multiple types. This class is very similar to a std::any, so I will be using this in this ...
- 33
2
votes
1
answer
169
views
C++17 view over the Ith elements of tuples in containers of tuples
For mainly didactic reasons, I have designed my ElementsView<I, T> class template, which provides a view over the I th ...
- 123
1
vote
2
answers
58
views
C++ variardic universal template for unknown types, used to handle multiple network protocols
I am creating a template function with variardic arguments, to handle a specific classes that have some interface, method, member or whatever is specialized in a specialization area. However I came to ...
- 215
3
votes
1
answer
1k
views
visit for std::any
While solving an online excersise I have written some basic implementation for a visit function that works with std::any.
The ...
- 459
2
votes
1
answer
478
views
Binding move-only objects to functions (for a thread pool implementation)
I recently implemented a thread pool using std::functions. I only supported functions taking no arguments on the assumption that there would be no need to have them ...
- 205
3
votes
1
answer
2k
views
Mapping between Enum <-> Enum <-> String view
I've been working on some kind of mapper that would allow me to map between types.
My objectives:
it should allow mapping between two enums
it should allow mapping enum to string_view
it should allow ...
- 241
2
votes
1
answer
272
views
An rough implementation of `std::is_constructible`
As a challenge/fun activity/task, I have implemented my version of std::is_constructible.
Here is the source code:
...
2
votes
1
answer
240
views
Implementation of versatile IIR digital filter in C++
I have realized that all the digital filters of the IIR type have the same structure. They are described by difference equation in following form:
$$
y(k) = b_0\cdot x(k) + b_1\cdot x(k-1) + \ldots +...
- 355
2
votes
0
answers
142
views
invocable_traits v5
Goal: implement traits that for anything callable return its arity, return type and the argument types. Since pointers to data members are also callable, those should be handled (and be considered 0-...
1
vote
1
answer
136
views
invocable_traits v4
Update: there is a new version of this code: v5 is posted here
Goal: implement traits that for anything callable return its arity, return type and the argument types. Since pointers to data members ...
3
votes
0
answers
54
views
invocable_traits v3
Update: there is a new version of this code: v4 is posted here
Goal: implement traits that for anything callable return its arity, return type and the argument types. Since pointers to data members ...
3
votes
1
answer
63
views
invocable_traits
Update: there are new versions of this code: v3 is posted here and v4 is posted here
Goal: implement traits that for anything callable return its arity, return type and the argument types. Since ...
3
votes
1
answer
763
views
c++20 compile time string utility v2
This is a follow up on c++20 compile time string utility, as suggested by G. Sliepen posted as a new question, so it can be reviewed on its own.
The following code has suggested improvements from the ...
- 85
5
votes
2
answers
3k
views
c++20 compile time string utility
While upgrading some meta-program running in production for years to the latest (c++20) standard, I rewrote this particular compile time string utility.
Even though this new version produces desired ...
- 85
1
vote
2
answers
605
views
Automatically registering a class using header-only templated classes
I'm trying to reduce the boilerplate of a lot of header-only classes I'm using. Each of these classes must go through a registration step. I want this step to be defined in the same file as the class ...
- 551
1
vote
1
answer
95
views
One-time dynamic, many-time *almost* static type dispatch
Annoyed at the tension between good software design principles that require well-defined delimitations between interface and implementations, and the requirements for critical code to run fast, which ...
- 141
8
votes
3
answers
4k
views
C++17 : Typelist manipulation
I'm reading "Modern C++ Design"(A. Alexandrescu, 2002) and practicing basic TMP in chapter 3. Typelists. Since the book is quite dated, I revised example codes in C++17-esque manner.
Feel ...
- 1,693
1
vote
1
answer
766
views
template function for conditional dereference
I don't know why there's no such function in std (at least I didn't find one). I need a conditional template function to return a reference to an object of T. ...
- 459
3
votes
1
answer
1k
views
Object to ignore unused function output parameters
In our software we have some functions that return information through lvalue reference parameters, which, in some cases, are irrelevant for the calling code. For that reason, I tried to come up with ...
- 133
1
vote
1
answer
267
views
Handle C++ templates in Qt5
Searching for a solution to my problem I've read many posts regarding templates in Qt (including those on SE) and didn't find a complete solution (or I should say a complete example of a solution) so ...
- 781
6
votes
1
answer
498
views
Implementing apply_each for tuple c++
I'm implementing apply_each for tuple-like object as a general function which may be a combined version of for_each and ...
- 195
2
votes
1
answer
206
views
Creating a structural type array wrapper to be qualified as non-type template parameter C++
I'm trying to replicate std::array but with modifications that I should put the private data member to the public so the class template ...
- 195
2
votes
1
answer
95
views
Computing nth Tribonacci number at compile time using C++ template metaprogramming facilities
I have this small C++ program for computing the \$n\$th Tribonacci number at compile-time. My main concern is: is it possible to get rid of the statickeyword (I had ...
- 27k
1
vote
1
answer
626
views
A multi key/value type "folded" map class template
I have recently come across a use case where I need to lump many maps into a single container. These maps can have different combinations of key/value types, but they all differ from one another.
For ...
- 173
4
votes
3
answers
3k
views
De-/Serialization of structs representing TCP messages
I wrote two template functions to serialize and deserialize structs representing messages to be sent and received via a TCP socket:
...
- 6,036
2
votes
0
answers
163
views
Generic way to access private/protected members
Motivation
I and the company is working on building C++ SDK automatically for several platforms, including Windows.
In summary, I have to test somehow if the private member of function pointers' type ...
- 121
6
votes
3
answers
1k
views
C++ Generic Callback class with removable listeners by unique id
I'm quite new to the STL.
Does this make sense? Is there a better way of removing the listeners instead of using shared_ptr while keeping the code short and simple? Is there something in the STL to ...
- 300
3
votes
1
answer
202
views
Implementation of the basic matrix operations for embedded application in C++
I have been developing a control software in C++ and for implementation of the control algorithms I need basic matrix operations like addition, subtraction, multiplication and multiplication by scalar....
- 385
1
vote
0
answers
176
views
"tuple with named fields" implementation
I'd like to show you a type I made while experimenting with literal, non-type template parameters in C++20.
The idea is to provide a type that wraps up tuple-like types (std::tuple, std::pair, even ...
- 261
2
votes
1
answer
1k
views
C++ generic, multi-dimensional linear interpolation template
Use-case in a nutshell: Interpolate fixed-sized data (a lookup table) that provides output values for combinations of a (fixed) number of inputs. The appropriate scaling is done externally, each axis ...
- 813
5
votes
1
answer
577
views
Binary IO inspired by struct pack
About
I'm writing a header-only template library for helping with binary IO. It is inspired by pack-d, which is in turn inspired by Python's struct module. I've only finished the output part and ...
- 151
1
vote
0
answers
203
views
Making std::optional a monad via SFINAE
To practice with SFINAE, template meta programming, functional programming and monads in C++, I decided to try writing a skinny version of the two functions (monadic binding and return) that make <...
- 547
4
votes
3
answers
415
views
Calculate the centroid of a collection of complex numbers
In working on another problem, one component I needed was to calculate the centroid of a collection of complex objects. The well-known way to calculate this is to simply average the real and ...
- 65.3k
0
votes
2
answers
3k
views
struct,template arguments, C++ [closed]
I am writing color model logic in C++. I ask review in defining limits for the color model, by saying Limits I mean this.
Consider a struct which represents ...
- 319
5
votes
1
answer
435
views
Using templates to wrap variardic JNI method calls into type-safe C++ functors
I am working on a project which uses JNI. More than once I fell over the absence of type safety working with the variardic function calls. So I came up with this module. It wraps the variardic JNI ...
- 161
2
votes
1
answer
47
views
Colour-model classes using CRTP
I want to implement color space logic.
So I started with creating some structs:
...
- 319
7
votes
1
answer
414
views
Generic test case templates
I often find that when I am writing, refactoring, or reviewing code that I want to do some simple testing. There are many existing test frameworks such as gtest and cppunit but my desire was to ...
- 65.3k
4
votes
1
answer
318
views
Template Metaprogramming and Modular Arithmetic
Story
I'm trying to become more familiar with template metaprogramming and practice more of it. I need to use modular arithmetic to solve certain problems and so I decided to write a general purpose ...
- 224
5
votes
1
answer
124
views
Compiletime (constexpr) Differential Equation System Description for use in Optimal Control
Background
In the field of optimal control, it is part of everyday business to solve ordinary differential equations numerically. A differential equation system or dynamic system describes e.g. the ...
- 306
4
votes
1
answer
589
views
Template Metaprogramming - Multidimensional Vector Declaration
[EDIT]
The question has been edited. Please make sure to read the summary at the end of the post. If you'd like me to make a new post with a cleaner explanation and better examples, tell me to do so ...
- 224
9
votes
2
answers
1k
views
How to simplify this C++ CRTP example?
I wanted a simple thing: being able to override a base class and just add one single getter. The bad thing is the base class does override some operators and will return the wrong type. I, therefore, ...
- 1,017