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Questions tagged [policy-based-design]

56 questions
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5 answers

What is the difference between a trait and a policy?

I have a class whose behavior I am trying to configure. template ServerTraits; Then later on I have my server object itself: template class Server {…}; My question is for my usage above…
Nathan Doromal
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Policy based design and best practices - C++

struct InkPen { void Write() { this->WriteImplementation(); } void WriteImplementation() { std::cout << "Writing using a inkpen" << std::endl; } }; struct BoldPen { void Write() { std::cout << "Writing using a boldpen"…
Navaneeth K N
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C++11 templates, determining return type

I am building a matrix library and I am trying to use the policy-based design. So my base classes are classes that provide a storage method and some access functions. I also have a function matrix which provides the mathematical functions. This…
Sparky
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2 answers

How to use typelists

I read about typelists in 'Modern C++ Design' and I understood it as some kind of union for types. By putting diffrent, non-related types in a typelist, one can use it to represent more than one type at once, without inheritance. I tested typelist…
DaClown
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Understanding the exposition of Alexandrescu about the weaknesses of multiple inheritance

UPDATE: I have asked a narrower question here. On pages 6-7 of Modern C++ Design, Andrei Alexandrescu gives a very fundamental discussion of the strengths and weaknesses of two C++ language features -- multiple inheritance and templates -- with…
AlwaysLearning
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C++ policy based design: Inheritance vs composition

At Meeting C++ 2019, Jon Kalb gave a talk about template techniques and mentioned policy classes. See here for the source: https://youtu.be/MLV4IVc4SwI?t=1815 The interesting code snippet in question is: template
flowit
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6
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Preserving the implicitness of construction in a policy-based class

Consider a policy-based smart pointer class Ptr with only one policy that will prevent dereferencing it in a NULL state (somehow). Let's consider 2 policies of this kind: NotNull NoChecking Since the NotNull policy is more restrictive, we would…
tsuki
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Does static polymorphism make sense for implementing an interface?

and Merry Christmas everybody! I am learning about static polymorphism and I'm reading Andrei Alexandrescu's excellent book on policy-based design. I came across the following, in my code: I have interface Interface which specifies that method Foo…
Dan Nestor
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Policy based approach with logger

I spend some time with redesigning a logger class I did once into a policy based approach after reading an article about policy based design and wanting to try something myself. Some code: template …
Chris
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5
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Partial specialization for a parent of multiple classes

I want to use partial specialization for a template class so that all children of that template class will use that specialization. Let me explain it with an example :) template < typename T, unsigned int rows, unsigned int cols> class BaseMatrix…
Sparky
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Is Mixin a special case of Policy-Based Design?

As far as I know, mixin is when you first write the derived class, and then you can inject the base class to it through a template parameter. Example: http://www.drdobbs.com/cpp/mixin-based-programming-in-c/184404445 As I know Policy-based design is…
Melkon
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Policy Based Design with Variadic Templates

I have a set of homogeneous policy classes that I want to pass as policies to a template class, PolicyDrivenClass, which takes some unknown number of policy template parameters. Each policy implements a "name" function, and I would like to be able…
Craig Wright
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What is a good tutorial for C++ policy-based class design?

I have just started reading Modern C++ Design Generic programming and Design Patterns Applied and I am wondering if I need to go through some very basic tutorial on policy-based class design before I dive in. Will chapter 1 provide all I need to…
dubnde
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Dispatch on execution policy by type or enum?

In C++ I basically have two choices in policy based design patterns: I can use individual types (based on which an overload is selected) or specify an enum that contains all policies and I would dispatch over them at runtime. What is the preferred…
glades
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What are the measures to call a Python code a policy-based design?

Description I wonder if the code I am showing can be considered as an example of policy-based design in Python. Also, I would like to know if have you seen python modules using something like this example so I can learn from them? I wrote more…
Victor Bazterra
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