Callback issues error: invalid use of non-static data member
EDIT: Updated clean reproducible example.
I'm a beginner in C++ with a few years experience with C, so apologies if I am going about this the wrong way. I have tried to break down the issue to as small an example of code as I can. In my code I have inherited a C callback function and inside this I want to trigger another callback from a class member.
I am having two issues:
a) I don't have an instance of Range in Callback and the callback does not have a void * param for me to use.
b) I am getting an error message
error: invalid use of non-static data member ‘Range::cbk’
I'm just starting to learn C++ and the rules of OOP so apologies if I am doing things that are fundamentally flawed.
#include <iostream>
#include <functional>
class Range
{
public:
typedef std::function<void()> TCallback;
TCallback cbk;
Range()
{
cbk = std::bind(&Range::RunTest, this);
}
void Close() {}
~Range() { Close(); }
void RunTest()
{
std::cout << "RunningTestn";
}
};
static void Callback(bool ev)
{
if (ev)
Range::cbk();
}
int main()
{
std::function<void(bool)> test;
Range r1;
test = std::bind(Callback, 1);
test(1);
return 0;
}
c++ class oop std
asked Nov 19 '18 at 23:10
tech 1990
14
|
show 8 more comments
EDIT: Updated clean reproducible example.
I'm a beginner in C++ with a few years experience with C, so apologies if I am going about this the wrong way. I have tried to break down the issue to as small an example of code as I can. In my code I have inherited a C callback function and inside this I want to trigger another callback from a class member.
I am having two issues:
a) I don't have an instance of Range in Callback and the callback does not have a void * param for me to use.
b) I am getting an error message
error: invalid use of non-static data member ‘Range::cbk’
I'm just starting to learn C++ and the rules of OOP so apologies if I am doing things that are fundamentally flawed.
#include <iostream>
#include <functional>
class Range
{
public:
typedef std::function<void()> TCallback;
TCallback cbk;
Range()
{
cbk = std::bind(&Range::RunTest, this);
}
void Close() {}
~Range() { Close(); }
void RunTest()
{
std::cout << "RunningTestn";
}
};
static void Callback(bool ev)
{
if (ev)
Range::cbk();
}
int main()
{
std::function<void(bool)> test;
Range r1;
test = std::bind(Callback, 1);
test(1);
return 0;
}
c++ class oop std
asked Nov 19 '18 at 23:10
tech 1990
14
1
Where is your Minimal, Complete, and Verifiable example?
– Lightness Races in Orbit
Nov 19 '18 at 23:41
1
Please provide Minimal, Complete, and Verifiable example. As is currently, it is hard to understand what your problem may be. Is the problem that you are trying to call method, as a static method? If you are calling it from outside theTestOne, it is marked asprivate, as well, as being non-static.
– Algirdas Preidžius
Nov 19 '18 at 23:43
@LightnessRacesinOrbit Updated to break down issue to as small an example as I could.
– tech 1990
Nov 20 '18 at 23:04
@AlgirdasPreidžius Updated to break down issue to as small an example as I could
– tech 1990
Nov 20 '18 at 23:05
It is unclear what you're asking or what you're trying to do.
– Killzone Kid
Nov 20 '18 at 23:22
|
show 8 more comments
EDIT: Updated clean reproducible example.
I'm a beginner in C++ with a few years experience with C, so apologies if I am going about this the wrong way. I have tried to break down the issue to as small an example of code as I can. In my code I have inherited a C callback function and inside this I want to trigger another callback from a class member.
I am having two issues:
a) I don't have an instance of Range in Callback and the callback does not have a void * param for me to use.
b) I am getting an error message
error: invalid use of non-static data member ‘Range::cbk’
I'm just starting to learn C++ and the rules of OOP so apologies if I am doing things that are fundamentally flawed.
#include <iostream>
#include <functional>
class Range
{
public:
typedef std::function<void()> TCallback;
TCallback cbk;
Range()
{
cbk = std::bind(&Range::RunTest, this);
}
void Close() {}
~Range() { Close(); }
void RunTest()
{
std::cout << "RunningTestn";
}
};
static void Callback(bool ev)
{
if (ev)
Range::cbk();
}
int main()
{
std::function<void(bool)> test;
Range r1;
test = std::bind(Callback, 1);
test(1);
return 0;
}
c++ class oop std
asked Nov 19 '18 at 23:10
tech 1990
14
EDIT: Updated clean reproducible example.
I'm a beginner in C++ with a few years experience with C, so apologies if I am going about this the wrong way. I have tried to break down the issue to as small an example of code as I can. In my code I have inherited a C callback function and inside this I want to trigger another callback from a class member.
I am having two issues:
a) I don't have an instance of Range in Callback and the callback does not have a void * param for me to use.
b) I am getting an error message
error: invalid use of non-static data member ‘Range::cbk’
I'm just starting to learn C++ and the rules of OOP so apologies if I am doing things that are fundamentally flawed.
#include <iostream>
#include <functional>
class Range
{
public:
typedef std::function<void()> TCallback;
TCallback cbk;
Range()
{
cbk = std::bind(&Range::RunTest, this);
}
void Close() {}
~Range() { Close(); }
void RunTest()
{
std::cout << "RunningTestn";
}
};
static void Callback(bool ev)
{
if (ev)
Range::cbk();
}
int main()
{
std::function<void(bool)> test;
Range r1;
test = std::bind(Callback, 1);
test(1);
return 0;
}
c++ class oop std
c++ class oop std
asked Nov 19 '18 at 23:10
tech 1990
14
asked Nov 19 '18 at 23:10
tech 1990
14
edited Nov 20 '18 at 23:49
asked Nov 19 '18 at 23:10
tech 1990
14
asked Nov 19 '18 at 23:10
tech 1990
14
asked Nov 19 '18 at 23:10
tech 1990
14
14
1
Where is your Minimal, Complete, and Verifiable example?
– Lightness Races in Orbit
Nov 19 '18 at 23:41
1
Please provide Minimal, Complete, and Verifiable example. As is currently, it is hard to understand what your problem may be. Is the problem that you are trying to call method, as a static method? If you are calling it from outside theTestOne, it is marked asprivate, as well, as being non-static.
– Algirdas Preidžius
Nov 19 '18 at 23:43
@LightnessRacesinOrbit Updated to break down issue to as small an example as I could.
– tech 1990
Nov 20 '18 at 23:04
@AlgirdasPreidžius Updated to break down issue to as small an example as I could
– tech 1990
Nov 20 '18 at 23:05
It is unclear what you're asking or what you're trying to do.
– Killzone Kid
Nov 20 '18 at 23:22
|
show 8 more comments
1
Where is your Minimal, Complete, and Verifiable example?
– Lightness Races in Orbit
Nov 19 '18 at 23:41
1
Please provide Minimal, Complete, and Verifiable example. As is currently, it is hard to understand what your problem may be. Is the problem that you are trying to call method, as a static method? If you are calling it from outside theTestOne, it is marked asprivate, as well, as being non-static.
– Algirdas Preidžius
Nov 19 '18 at 23:43
@LightnessRacesinOrbit Updated to break down issue to as small an example as I could.
– tech 1990
Nov 20 '18 at 23:04
@AlgirdasPreidžius Updated to break down issue to as small an example as I could
– tech 1990
Nov 20 '18 at 23:05
It is unclear what you're asking or what you're trying to do.
– Killzone Kid
Nov 20 '18 at 23:22
1
1
Where is your Minimal, Complete, and Verifiable example?
– Lightness Races in Orbit
Nov 19 '18 at 23:41
Where is your Minimal, Complete, and Verifiable example?
– Lightness Races in Orbit
Nov 19 '18 at 23:41
1
1
Please provide Minimal, Complete, and Verifiable example. As is currently, it is hard to understand what your problem may be. Is the problem that you are trying to call method, as a static method? If you are calling it from outside the
TestOne, it is marked as private, as well, as being non-static.– Algirdas Preidžius
Nov 19 '18 at 23:43
Please provide Minimal, Complete, and Verifiable example. As is currently, it is hard to understand what your problem may be. Is the problem that you are trying to call method, as a static method? If you are calling it from outside the
TestOne, it is marked as private, as well, as being non-static.– Algirdas Preidžius
Nov 19 '18 at 23:43
@LightnessRacesinOrbit Updated to break down issue to as small an example as I could.
– tech 1990
Nov 20 '18 at 23:04
@LightnessRacesinOrbit Updated to break down issue to as small an example as I could.
– tech 1990
Nov 20 '18 at 23:04
@AlgirdasPreidžius Updated to break down issue to as small an example as I could
– tech 1990
Nov 20 '18 at 23:05
@AlgirdasPreidžius Updated to break down issue to as small an example as I could
– tech 1990
Nov 20 '18 at 23:05
It is unclear what you're asking or what you're trying to do.
– Killzone Kid
Nov 20 '18 at 23:22
It is unclear what you're asking or what you're trying to do.
– Killzone Kid
Nov 20 '18 at 23:22
|
show 8 more comments
1 Answer
1
active
oldest
votes
You can't call a member function without an instance.
You did it right in the Range constructor; you did it wrong in main and Callback.
static void Callback(Range* ptr, bool ev)
{
if (ev)
ptr->cbk();
}
And:
test = std::bind(Callback, &r1, 1);
// ^^^^^
If you can't change Callback, then what you want to do is simply impossible. You'd have to have some global Range pointer, but this is really minging. Ultimately it's why classes were invented but if you can't use them because you're stuck with a really flat C API then you just have to hack around it like you would in C.
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick avoid*in there for passing information.
– Lightness Races in Orbit
Nov 21 '18 at 11:43
add a comment |
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1 Answer
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1 Answer
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oldest
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oldest
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oldest
votes
You can't call a member function without an instance.
You did it right in the Range constructor; you did it wrong in main and Callback.
static void Callback(Range* ptr, bool ev)
{
if (ev)
ptr->cbk();
}
And:
test = std::bind(Callback, &r1, 1);
// ^^^^^
If you can't change Callback, then what you want to do is simply impossible. You'd have to have some global Range pointer, but this is really minging. Ultimately it's why classes were invented but if you can't use them because you're stuck with a really flat C API then you just have to hack around it like you would in C.
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick avoid*in there for passing information.
– Lightness Races in Orbit
Nov 21 '18 at 11:43
add a comment |
You can't call a member function without an instance.
You did it right in the Range constructor; you did it wrong in main and Callback.
static void Callback(Range* ptr, bool ev)
{
if (ev)
ptr->cbk();
}
And:
test = std::bind(Callback, &r1, 1);
// ^^^^^
If you can't change Callback, then what you want to do is simply impossible. You'd have to have some global Range pointer, but this is really minging. Ultimately it's why classes were invented but if you can't use them because you're stuck with a really flat C API then you just have to hack around it like you would in C.
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick avoid*in there for passing information.
– Lightness Races in Orbit
Nov 21 '18 at 11:43
add a comment |
You can't call a member function without an instance.
You did it right in the Range constructor; you did it wrong in main and Callback.
static void Callback(Range* ptr, bool ev)
{
if (ev)
ptr->cbk();
}
And:
test = std::bind(Callback, &r1, 1);
// ^^^^^
If you can't change Callback, then what you want to do is simply impossible. You'd have to have some global Range pointer, but this is really minging. Ultimately it's why classes were invented but if you can't use them because you're stuck with a really flat C API then you just have to hack around it like you would in C.
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
You can't call a member function without an instance.
You did it right in the Range constructor; you did it wrong in main and Callback.
static void Callback(Range* ptr, bool ev)
{
if (ev)
ptr->cbk();
}
And:
test = std::bind(Callback, &r1, 1);
// ^^^^^
If you can't change Callback, then what you want to do is simply impossible. You'd have to have some global Range pointer, but this is really minging. Ultimately it's why classes were invented but if you can't use them because you're stuck with a really flat C API then you just have to hack around it like you would in C.
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
answered Nov 21 '18 at 10:23
Lightness Races in Orbit
284k51460781
284k51460781
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick avoid*in there for passing information.
– Lightness Races in Orbit
Nov 21 '18 at 11:43
add a comment |
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick avoid*in there for passing information.
– Lightness Races in Orbit
Nov 21 '18 at 11:43
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
Thanks very much for the input; yes this is exactly the issue I can't change the declaration of Callback. I will probably go down the global pointer route even though I will need an array of global pointers for multiple instances. As ugly as this it seems my only option.
– tech 1990
Nov 21 '18 at 11:27
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick a
void* in there for passing information.– Lightness Races in Orbit
Nov 21 '18 at 11:43
@tech1990 Pretty much. As an aside the callback is poorly designed because, knowing that this was always a problem, people tended to at least stick a
void* in there for passing information.– Lightness Races in Orbit
Nov 21 '18 at 11:43
add a comment |
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1
Where is your Minimal, Complete, and Verifiable example?
– Lightness Races in Orbit
Nov 19 '18 at 23:41
1
Please provide Minimal, Complete, and Verifiable example. As is currently, it is hard to understand what your problem may be. Is the problem that you are trying to call method, as a static method? If you are calling it from outside the
TestOne, it is marked asprivate, as well, as being non-static.– Algirdas Preidžius
Nov 19 '18 at 23:43
@LightnessRacesinOrbit Updated to break down issue to as small an example as I could.
– tech 1990
Nov 20 '18 at 23:04
@AlgirdasPreidžius Updated to break down issue to as small an example as I could
– tech 1990
Nov 20 '18 at 23:05
It is unclear what you're asking or what you're trying to do.
– Killzone Kid
Nov 20 '18 at 23:22