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
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c++ how to call outer class's function from a functor?
I have a functor defined within a class.
I want to access member function of the outer class directly from the functor.
How do I do that? I want to pass this functor to a template class elsewhere in the code. I dont want to use function…
bsobaid
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2 answers
Declaring and defining a function object inside a class member function
I wonder if and how it is possible to define a function object inside a classes member function to use it directly with, for example, the std::transform function.
I know the example is a bit stupid, it's just to show the problem I'm confronted with.…
PiJ
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0 answers
Instantiating Function Object with unbound Function Objects leads to l-value error
I have the following function objects:
/// function object wrapping node and label data into strings of DOT code
/// requires as template parameters 2 function objects that define behaviour
/// converting node and lable into strings. Requires as…
lo tolmencre
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1 answer
questions about function object in C++
I have a question regarding the following piece of code.
template
struct DisplayElementKeepCount
{
int m_nCount;
DisplayElementKeepCount () { m_nCount = 0; }
void operator () (const T& element){++ m_nCount; cout<
Sarah
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2 answers
create dynamic functions keeping state
Python beginner question. Say you want to dynamically create a function that keeps some state (in the code below an integer i). Then as the function defined is an object, we could use it later on. In the following code, I add the functions to a…
aaragon
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0
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1 answer
Assigning a Function to a Function Object's Property
I have a JavaScript function object defined like this:
var minimal = (function() {
var handler = undefined;
var test = function() {
console.log(typeof handler);
if (typeof handler === 'function') {
handler();
…
Sonny
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1 answer
Understanding MyClass x(y); where y is of type MyClass
I have the following code that is part of an exercise (about which I asked here).
class MyInt
{
public:
MyInt(int x) : MyValue(new int(x)){};
MyInt()
{
MyValue = 0;
}
private:
int* MyValue;
}
int main(int argc,char** argv)
{
…
Kae
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0
votes
1 answer
Should I receive a function by copy, reference or const reference?
When defining a function that takes a function parameter, should I receive a lambda/std::function by copy, reference or const reference?
Or all three?
leewz
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0
votes
2 answers
make_heap on std::map with user defined comparison & random access iterator
I have a map defined like this
std::map myMap;
After processing this map I want to treat it as a heap (based on the second value). I decided to use std::make_heap function.. which is defined like this...
template< class RandomIt, class…
vikrant
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0
votes
1 answer
Using a function object when the API asks for a function pointer
I want to call a C API from C++. The API expects a function pointer, though for me the functionality is implemented in a C++ function object because it has state.
In fact the desired functionaliity is split across into two function objects. The C…
san
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0
votes
2 answers
C++ std:sort() using different criteria
I searched a lot and I am not sure if this is query is repeated but I used this as an reference to create a sort for my std::vector which takes data of following type.
typedef struct {
int size;
int type;
int id;
} AC;
I was able to …
Recker
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5 answers
for_each usage in C++
#include
-
#include
Sachin Shetye
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1 answer
how to use a function object as a custom comparator for accessing a local variable instead of using a lambda function in C++?
I am trying to learn priority_queue concept in C++, and I came across this interview question. Although, I managed to solve this problem with a lambda function, I could not figure out how to do the same operation with a custom comparator as a…
albin
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-1
votes
1 answer
the differences between function-object and function-pointer?
i defined a class, then save the pointer to Foo in the priority_queue, and use the cmp-function that i defined.
but if the cmp-funtion calls the function-object, an error occurs:
class Foo
{
friend bool cmp(Foo *, Foo *);
public:
Foo() =…
Wonter
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-1
votes
3 answers
Python - Pass named arguments to function object
I received a call about stale parameters in a web app. I saw this post...
wtforms+flask today's date as a default value
... which was spot on.
The field's default was getting set on web server start. It was easy to test. A couple of print…
MrGoodfix
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