logo
down
shadow

Class's operator() or bind a function as a functor?


Class's operator() or bind a function as a functor?

Content Index :

Class's operator() or bind a function as a functor?
Tag : performance , By : quicky
Date : November 25 2020, 01:01 AM


Comments
No Comments Right Now !

Boards Message :
You Must Login Or Sign Up to Add Your Comments .

Share : facebook icon twitter icon

How do you write a operator() or less-than-functor neater than a trivalue-compare-function


Tag : cpp , By : Killercode
Date : March 29 2020, 07:55 AM
hope this fix your issue The thing is that you are fine with just declaring one trivalue compare function if you autogenerate all operators using: http://en.wikipedia.org/wiki/Barton%E2%80%93Nackman_trick

Why functor result bind to new module name is necessary for call nested functor of?


Tag : ocaml , By : Sanoran
Date : March 29 2020, 07:55 AM
this will help While I don't believe that this restriction is strictly necessary, it is probably motivated by certain limitations in OCaml's module type system. Without going into too much technical detail, OCaml requires all intermediate module types to be expressible as syntactic signatures. But with functors, that sometimes isn't possible. For example, consider:
module Functor(X : sig end) = struct
  type t = T of int
  module Nested(Y : sig end) = struct let x = T 5 end 
end
functor(Y : sig end) -> sig val x : Functor(struct end).t end  (* not legal OCaml! *)
module A = Functor(struct end)
functor(Y : sig end) -> sig val x : A.t end

Using operator new as a functor/function pointer


Tag : cpp-11 , By : Carlos Galdino
Date : March 29 2020, 07:55 AM
I hope this helps . In C++11, let's say I have a function that takes a functor/function and it forwards the arguments to that function. I can pass in a pointer to std::make_shared, which causes it to instantiate a class and call its contructor. But what is the equivalent to doing this with a raw operator new instead? It seems like std::allocator is what I should use, but the construct function there requires a pointer to the allocated memory. I can make it work by wrapping the new call into the template function new_object, but it seems like there should be a way for me to retrieve that function pointer directly. , Why not something like this?
   std::allocator<foo> alloc;
   do_something(std::bind(&std::allocator<foo>::construct<foo, int, std::string>, &alloc, alloc.allocate(sizeof(foo)), std::placeholders::_1, std::placeholders::_2), 12, "test2");

boost function to any functor with template operator ()


Tag : cpp , By : user183954
Date : March 29 2020, 07:55 AM
I hope this helps you . boost::function, just like std::function requires a specific functor signature (in your case void(void*)), which is the signature it will try to call your functor with. That's why T is deduced as void and the compiler refuses to give you a void&, rightfully so.
Your example is fundamentally add odds with itself, because if you want to have type erasure, you cannot have templates, as the compiler cannot know which templates to instantiate otherwise. Assume for a moment that boost::function could do what you want.
void foo(boost::function<magic> func)
{
    double a = 5;   
    func(&a);
}

Can I pass a Functor class(that overloads operator()) to a function, that wants a function pointer? And how


Tag : cpp , By : user185939
Date : March 29 2020, 07:55 AM
hop of those help? Traditional way for callback to allow extra parameter is to have extra void* that user provides.
using callback = bool (int, int, void* userData);

bool run_callback(int a, int b, void* userData) {
    CallBack* c = reinterpret_cast<void*>(userData);

    return (*c)(a, b);
}

CallBack t(true);
Register(&run_callback, &t); // Would call later run_callback(2, 3, &t);
Callback* global = nullptr;

bool RunCallBack(int foo, int bar)
{
    assert(global != nullptr);
    return (*global)(foo, bar);
}
Callback f(false);
Callback t(true);

global = &f;
print_result(&RunCallBack, 2, 3);
global = &t;
print_result(&RunCallBack, 2, 3);
Related Posts Related QUESTIONS :
  • Why AQTime slows execution even when profiling is not on, and can anything be done for it?
  • Very slow guards in my monadic random implementation (haskell)
  • Oracle: Insertion on an indexed table, avoiding duplicates. Looking for tips and advice
  • What's the best way to store Logon User information for Web Application?
  • Best way to retrieve certain field of all documents returned by a Lucene search
  • CakePHP - Set recursive to -1 in AppModel then use Containable behaviour as appropriate
  • Memory Bandwidth Performance for Modern Machines
  • How measure Web App performance?
  • Is there a way to throttle or limit resources used by a user in Oracle?
  • NFData instance for the Coyoneda type
  • OpenGL drops performance when writing to nonzero FBO attachment on AMD
  • How does HasCallStack influence the performance of a normal branch in Haskell?
  • Performance load testing using Jmeter and how assets files may affect the results
  • Best practice and performance for global variables
  • LINQ: Improving performance of "query to find all dictionaries from list of dictionaries where given key has at lea
  • Removing duplicates from CSV -- performance problems
  • Why is `_mm_stream_si128` much slower than `_mm_storeu_si128` on Skylake-Xeon when writing parts of 2 cache lines? But l
  • Why the array arrangment affects speedup?
  • How to display actual loop count in JMeter
  • Spark: Explicit caching can interfere with Catalyst optimizer's ability to optimize some queries?
  • How to remove some items from an arraylist without loop and less time complexity?
  • Why is my program slow when access 4K offset array element?
  • Is static sql to be preferred over dynamic sql in postgresql stored procedures?
  • Which is generally faster to test for zero in x86 ASM: "TEST EAX, EAX" versus "TEST AL, AL"?
  • postgres functions: when does IMMUTABLE hurt performance?
  • Concurrent user Test using Jmeter
  • How to gauge Excel Calculation speed?
  • Performance of NewRelic Real User Monitoring
  • T-SQL - wrong query execution plan behaviour
  • is it worth it to convert graphics from jpg to png?
  • async and await: are they bad?
  • Determining algorithm's runtime using Big-O notation
  • How to use one big query instead of one by one queries in Yii2 Kartik GridView?
  • r-contiguous matching, MATLAB
  • Labels, properties, or nodes? Cypher/Neo4j
  • Intel Intrinsics guide - Latency and Throughput
  • Tensorflow GPU utilization only 60% (GTX 1070)
  • Multiple Inline declaration vs Reuse of variables
  • Scala: call by name and call by value performance
  • Check if bracket order is valid
  • How to increase performance in neo4j?
  • How to sort a matrix based on the number of occurrences of a particular value in a corresponding column without using fo
  • Perl speed: difference between $a = $a.$b and $a .= $b
  • Which is faster in c++11: max(a-b, b-a) or abs(a-b)?
  • Google Search Appliances versus Microsoft Enterprise Search (FAST)
  • map vs switch performance in go
  • When will simple parallization not offer a speedup?
  • AI Chess Valid Moves
  • LINQ to Objects Optimization Techniques?
  • Comparing performance of software implementations
  • Website performacne - Move the ad loading function(GA_googleFillSlot) to the bottom on page
  • Three.js performance optimization with 10000 meshes
  • "Fast" way to measure code execution time
  • Monitoring my web application performance from the client browser
  • How do I interpret this difference in matrix multiplication GFLOP/s?
  • Why is this simple Haskell program so slow?
  • Why is my pixel manipulation function so slow?
  • How to correctly dockerize and continuously integrate 20GB raw data?
  • Will errorWithoutStackTrace be faster than error when there isn't HasCallStack?
  • Check permission; always a request against database?
  • shadow
    Privacy Policy - Terms - Contact Us © scrbit.com