In object-oriented languages, function object (also known as functor) is a feature that allows objects to be used like if they were ordinary functions.
Questions tagged [function-object]
168 questions
2
votes
1 answer
Assign a method operator() to an object
I'm having this problem in a real-world Project.
How to convert an "object" into a function in JavaScript?
I need at least as Steve said "to assign a method operator() to an object".
Re-assign is not an option, because the object is too complex and…
Gus
- 25,839
- 2
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2
votes
1 answer
std::set - like function object support in my container
I have implemented my own container:
template
class MyContainer
{
// body where in some point 2 elements of collection are compared (-1, 0 and 1 possible comparison results)
};
What I want to do is add support of function objects,…
Przemysław Kalita
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- 3
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- 28
2
votes
1 answer
How to accumulate results from a member function of a Element in a Container using only Element member functions and STL?
I have a Container of Elements, and each Element has its size() member function. I have managed to accumulate the total Container Elements size by writing a binary operation add_size:
#include
#include
#include…
tmaric
- 5,347
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- 75
2
votes
1 answer
C++ function objects cannot create sum using std::for_each (VS2012)
I am having trouble using function-objects in Visual Studio 2012.
I created a simple std::vector, added the ints 0-9 and wanted to create the sum of it using a function object. My class definition (inline):
template
class Sum {
private:
…
bash.d
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2
votes
2 answers
Passing inner function of a struct (or class) as a functor
How should I pass a function inside an struct as a functor? I assumed this should work fine, but it didn't:
#include
using namespace std;
struct s {
int a[10];
bool cmp(int i, int j) {
// return something
}
…
semekh
- 3,867
- 2
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- 34
2
votes
2 answers
get state in a function object casted to a std::function
I want to retrieve state from a function object. But the function object has been casted to a function<> template. How can I do it?
I mean:
function object:
class Counter {
private:
int counter_;
public:
Counter():counter_(0) {cout <<…
jamarier
- 23
- 2
1
vote
2 answers
overloading operator ()
I have this declaration
struct Z {
void operator ()( int a ) {
cout << "operator()() " << a << endl;
}
};
Z oz, *zp = &oz;
oz(1); //ok
(*zp)(2); //ok
zp(3); //"error: 'zp' cannot be used as a function"
Is there a way to modify…
Ulterior
- 2,786
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1
vote
2 answers
Bind function pointer to boost::function object
How can I initialize a boost::function object with a raw function pointer?
Metacode
extern "C"
{
class Library
{
...
};
Library* createLibrary();
}
...
void* functionPtr =…
Mythli
- 5,995
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1
vote
1 answer
how to save any callable in c++ template class
I wanted to define a scopeguard, which runs some clean up code when scope exit.
And I don't want to use std::function since it has some overhead. Then I come up with this implementation that is templated.
template
class…
doraemon
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1
vote
1 answer
Can a javascript Function object be called?
This is weird! I am struggling hard with the problem that javascript Proxy handler's apply trap does not get the Proxy itself passed as an argument, only the naked function. But I need to pass along some metadata to use for re-wrapping function…
Gunther Schadow
- 1,490
- 13
- 22
1
vote
2 answers
How to run do_n?
I'm currently working on recursive function on Think Python, page 44.
It wrote:
"Write a function called do_n that takes a function object and a number, n as arguments,
and that calls the given function n times."
I found a really good answer from…
JimBigMac
- 19
- 6
1
vote
3 answers
STL and std custom compare arguments working in c++
I asked this question on stackoverflow STL passing object
I got to know that we pass objects which in tern call the compare operator in them and compare our values and gives us a result. All good.
Now in this piece of code:
class Compare {
…
Shobhit Tewari
- 535
- 5
- 20
1
vote
1 answer
How to sort a vector with given column only on a triplet value?
I have a struct with three int in it.
struct x{
int a,
b,
c;
};
I am using the struct to store triplets in the vector as the triplets will represent source, destination and weight.
vector myVec;
and I am adding values in it with…
vhmvd
- 192
- 3
- 15
1
vote
1 answer
Using smart pointers within multi-threaded application
I have some calculation I need to perform that is dependent on two or more steps as follows:
class A
{
public:
double step1() { return 2.5; }
};
class B
{
public:
double step2() { return 1.2; }
};
class Result
{
public:
…
Charlie H.
- 70
- 3
1
vote
2 answers
Passing function objects and using them in other functions in Python 3.8.4
I was looking at this question:
cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first and last element of that pair. For example, car(cons(3, 4)) returns 3, and cdr(cons(3, 4)) returns 4.
Given this implementation of cons:
def…
Spencer Felton
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