Can I use C++11 lambda with libevent?
There is a callback function type in libevent used by event_new().
typedef void (*event_callback_fn)(evutil_socket_t, short, void *);
I want use lambda with event_callback_fn.
If I use
(evutil_socket_t fd, short flags, void * _param){}
everything is OK.
But if I use the lambda capture list
[&](evutil_socket_t fd, short flags, void * _param){}
event_new() will not be compiled.
c++11 lambda libevent boost-lambda
asked Nov 22 at 9:37
DinoStray
1298
add a comment |
There is a callback function type in libevent used by event_new().
typedef void (*event_callback_fn)(evutil_socket_t, short, void *);
I want use lambda with event_callback_fn.
If I use
(evutil_socket_t fd, short flags, void * _param){}
everything is OK.
But if I use the lambda capture list
[&](evutil_socket_t fd, short flags, void * _param){}
event_new() will not be compiled.
c++11 lambda libevent boost-lambda
asked Nov 22 at 9:37
DinoStray
1298
2
Only a capture-less lambda may be converted to a pointer to functions. If you need captures then you need to solve it some other way.
– Some programmer dude
Nov 22 at 9:40
Short answer is no. You should understand what closures and callbacks are. However, you could pass the closure as thevoid *client data
– Basile Starynkevitch
Nov 22 at 9:40
@ Basile Starynkevitch, so event_new(_base, -1, EV_TIMEOUT, (evutil_socket_t fd, short flags, void * _param){ }, (){}); like this? still compile error
– DinoStray
Nov 22 at 9:49
add a comment |
There is a callback function type in libevent used by event_new().
typedef void (*event_callback_fn)(evutil_socket_t, short, void *);
I want use lambda with event_callback_fn.
If I use
(evutil_socket_t fd, short flags, void * _param){}
everything is OK.
But if I use the lambda capture list
[&](evutil_socket_t fd, short flags, void * _param){}
event_new() will not be compiled.
c++11 lambda libevent boost-lambda
asked Nov 22 at 9:37
DinoStray
1298
There is a callback function type in libevent used by event_new().
typedef void (*event_callback_fn)(evutil_socket_t, short, void *);
I want use lambda with event_callback_fn.
If I use
(evutil_socket_t fd, short flags, void * _param){}
everything is OK.
But if I use the lambda capture list
[&](evutil_socket_t fd, short flags, void * _param){}
event_new() will not be compiled.
c++11 lambda libevent boost-lambda
c++11 lambda libevent boost-lambda
asked Nov 22 at 9:37
DinoStray
1298
asked Nov 22 at 9:37
DinoStray
1298
asked Nov 22 at 9:37
DinoStray
1298
asked Nov 22 at 9:37
DinoStray
1298
asked Nov 22 at 9:37
DinoStray
1298
1298
2
Only a capture-less lambda may be converted to a pointer to functions. If you need captures then you need to solve it some other way.
– Some programmer dude
Nov 22 at 9:40
Short answer is no. You should understand what closures and callbacks are. However, you could pass the closure as thevoid *client data
– Basile Starynkevitch
Nov 22 at 9:40
@ Basile Starynkevitch, so event_new(_base, -1, EV_TIMEOUT, (evutil_socket_t fd, short flags, void * _param){ }, (){}); like this? still compile error
– DinoStray
Nov 22 at 9:49
add a comment |
2
Only a capture-less lambda may be converted to a pointer to functions. If you need captures then you need to solve it some other way.
– Some programmer dude
Nov 22 at 9:40
Short answer is no. You should understand what closures and callbacks are. However, you could pass the closure as thevoid *client data
– Basile Starynkevitch
Nov 22 at 9:40
@ Basile Starynkevitch, so event_new(_base, -1, EV_TIMEOUT, (evutil_socket_t fd, short flags, void * _param){ }, (){}); like this? still compile error
– DinoStray
Nov 22 at 9:49
2
2
Only a capture-less lambda may be converted to a pointer to functions. If you need captures then you need to solve it some other way.
– Some programmer dude
Nov 22 at 9:40
Only a capture-less lambda may be converted to a pointer to functions. If you need captures then you need to solve it some other way.
– Some programmer dude
Nov 22 at 9:40
Short answer is no. You should understand what closures and callbacks are. However, you could pass the closure as the
void * client data– Basile Starynkevitch
Nov 22 at 9:40
Short answer is no. You should understand what closures and callbacks are. However, you could pass the closure as the
void * client data– Basile Starynkevitch
Nov 22 at 9:40
@ Basile Starynkevitch, so event_new(_base, -1, EV_TIMEOUT, (evutil_socket_t fd, short flags, void * _param){ }, (){}); like this? still compile error
– DinoStray
Nov 22 at 9:49
@ Basile Starynkevitch, so event_new(_base, -1, EV_TIMEOUT, (evutil_socket_t fd, short flags, void * _param){ }, (){}); like this? still compile error
– DinoStray
Nov 22 at 9:49
add a comment |
1 Answer
1
active
oldest
votes
The type alias
void (*event_callback_fn)(evutil_socket_t, short, void *);
is a function pointer. Lambdas can automatically convert to function pointers, when they don't capture anything. As soon as you define a closure (stateful lambda), you can't pass it as an argument of type event_callback_fn.
answered Nov 22 at 9:40
lubgr
10.2k21745
add a comment |
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1 Answer
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1 Answer
1
active
oldest
votes
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oldest
votes
active
oldest
votes
The type alias
void (*event_callback_fn)(evutil_socket_t, short, void *);
is a function pointer. Lambdas can automatically convert to function pointers, when they don't capture anything. As soon as you define a closure (stateful lambda), you can't pass it as an argument of type event_callback_fn.
answered Nov 22 at 9:40
lubgr
10.2k21745
add a comment |
The type alias
void (*event_callback_fn)(evutil_socket_t, short, void *);
is a function pointer. Lambdas can automatically convert to function pointers, when they don't capture anything. As soon as you define a closure (stateful lambda), you can't pass it as an argument of type event_callback_fn.
answered Nov 22 at 9:40
lubgr
10.2k21745
add a comment |
The type alias
void (*event_callback_fn)(evutil_socket_t, short, void *);
is a function pointer. Lambdas can automatically convert to function pointers, when they don't capture anything. As soon as you define a closure (stateful lambda), you can't pass it as an argument of type event_callback_fn.
answered Nov 22 at 9:40
lubgr
10.2k21745
The type alias
void (*event_callback_fn)(evutil_socket_t, short, void *);
is a function pointer. Lambdas can automatically convert to function pointers, when they don't capture anything. As soon as you define a closure (stateful lambda), you can't pass it as an argument of type event_callback_fn.
answered Nov 22 at 9:40
lubgr
10.2k21745
answered Nov 22 at 9:40
lubgr
10.2k21745
answered Nov 22 at 9:40
lubgr
10.2k21745
answered Nov 22 at 9:40
lubgr
10.2k21745
10.2k21745
add a comment |
add a comment |
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2
Only a capture-less lambda may be converted to a pointer to functions. If you need captures then you need to solve it some other way.
– Some programmer dude
Nov 22 at 9:40
Short answer is no. You should understand what closures and callbacks are. However, you could pass the closure as the
void *client data– Basile Starynkevitch
Nov 22 at 9:40
@ Basile Starynkevitch, so event_new(_base, -1, EV_TIMEOUT, (evutil_socket_t fd, short flags, void * _param){ }, (){}); like this? still compile error
– DinoStray
Nov 22 at 9:49