Mixing
Co-Dependent Definitions in C
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Suppose we have a function pointer on a struct, which has the struct itself as the first argument, a typical callback scenario.
typedef void (*callback_type)(my_struct_type *mst, int whatever);
typedef struct {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
This produces a compiler error on the first typedef, as one might expect. error: unknown type name my_struct_type. Reversing the definitions produces the same result, but the unknown type is callback_type.
The easy solution is to do the following:
typedef struct my_struct_type_S {
// lots of fun stuff
void (*notify_me)(my_struct_type_S *mst, int whatever);
} my_struct_type;
However, doing this elides the function pointer type definition, which it would be nice to be able to easily refer to later, and use for static type checks, nice error messages, etc.
Any suggestions on how to resolve this?
Edit on "possible duplicate":
This scenario involves function pointer typedefs that are arcane to many people. I think this is a good example for that case, and additionally, the accepted answer is very clean, clear, and simple.
c conventions
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
add a comment |
Suppose we have a function pointer on a struct, which has the struct itself as the first argument, a typical callback scenario.
typedef void (*callback_type)(my_struct_type *mst, int whatever);
typedef struct {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
This produces a compiler error on the first typedef, as one might expect. error: unknown type name my_struct_type. Reversing the definitions produces the same result, but the unknown type is callback_type.
The easy solution is to do the following:
typedef struct my_struct_type_S {
// lots of fun stuff
void (*notify_me)(my_struct_type_S *mst, int whatever);
} my_struct_type;
However, doing this elides the function pointer type definition, which it would be nice to be able to easily refer to later, and use for static type checks, nice error messages, etc.
Any suggestions on how to resolve this?
Edit on "possible duplicate":
This scenario involves function pointer typedefs that are arcane to many people. I think this is a good example for that case, and additionally, the accepted answer is very clean, clear, and simple.
c conventions
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
1
Possible duplicate of Structs that refer to each other
– chriptus13
Jan 3 at 3:16
add a comment |
Suppose we have a function pointer on a struct, which has the struct itself as the first argument, a typical callback scenario.
typedef void (*callback_type)(my_struct_type *mst, int whatever);
typedef struct {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
This produces a compiler error on the first typedef, as one might expect. error: unknown type name my_struct_type. Reversing the definitions produces the same result, but the unknown type is callback_type.
The easy solution is to do the following:
typedef struct my_struct_type_S {
// lots of fun stuff
void (*notify_me)(my_struct_type_S *mst, int whatever);
} my_struct_type;
However, doing this elides the function pointer type definition, which it would be nice to be able to easily refer to later, and use for static type checks, nice error messages, etc.
Any suggestions on how to resolve this?
Edit on "possible duplicate":
This scenario involves function pointer typedefs that are arcane to many people. I think this is a good example for that case, and additionally, the accepted answer is very clean, clear, and simple.
c conventions
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
Suppose we have a function pointer on a struct, which has the struct itself as the first argument, a typical callback scenario.
typedef void (*callback_type)(my_struct_type *mst, int whatever);
typedef struct {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
This produces a compiler error on the first typedef, as one might expect. error: unknown type name my_struct_type. Reversing the definitions produces the same result, but the unknown type is callback_type.
The easy solution is to do the following:
typedef struct my_struct_type_S {
// lots of fun stuff
void (*notify_me)(my_struct_type_S *mst, int whatever);
} my_struct_type;
However, doing this elides the function pointer type definition, which it would be nice to be able to easily refer to later, and use for static type checks, nice error messages, etc.
Any suggestions on how to resolve this?
Edit on "possible duplicate":
This scenario involves function pointer typedefs that are arcane to many people. I think this is a good example for that case, and additionally, the accepted answer is very clean, clear, and simple.
c conventions
c conventions
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
edited Jan 5 at 1:43
PyroAVR
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
asked Jan 3 at 3:10
PyroAVRPyroAVR
3591415
3591415
1
Possible duplicate of Structs that refer to each other
– chriptus13
Jan 3 at 3:16
add a comment |
1
Possible duplicate of Structs that refer to each other
– chriptus13
Jan 3 at 3:16
1
1
Possible duplicate of Structs that refer to each other
– chriptus13
Jan 3 at 3:16
Possible duplicate of Structs that refer to each other
– chriptus13
Jan 3 at 3:16
add a comment |
2 Answers
2
active
oldest
votes
You can do this by giving the struct a tag and using a forward declaration of the struct. Then you can use the typedef for the function pointer, and subsequently complete the definition of the struct.
typedef struct my_struct_type_S my_struct_type;
typedef void (*callback_type)(my_struct_type *mst, int whatever);
struct my_struct_type_S {
// lots of fun stuff
callback_type notify_me;
};
answered Jan 3 at 3:19
dbushdbush
104k14109146
1
With the emphasis on the forward declaration part:)
– David C. Rankin
Jan 3 at 3:21
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
add a comment |
You need to define the tag of the struct
typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
typedef struct _my_struct_type {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
answered Jan 3 at 3:20
chriptus13chriptus13
244413
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
You can do this by giving the struct a tag and using a forward declaration of the struct. Then you can use the typedef for the function pointer, and subsequently complete the definition of the struct.
typedef struct my_struct_type_S my_struct_type;
typedef void (*callback_type)(my_struct_type *mst, int whatever);
struct my_struct_type_S {
// lots of fun stuff
callback_type notify_me;
};
answered Jan 3 at 3:19
dbushdbush
104k14109146
1
With the emphasis on the forward declaration part:)
– David C. Rankin
Jan 3 at 3:21
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
add a comment |
You can do this by giving the struct a tag and using a forward declaration of the struct. Then you can use the typedef for the function pointer, and subsequently complete the definition of the struct.
typedef struct my_struct_type_S my_struct_type;
typedef void (*callback_type)(my_struct_type *mst, int whatever);
struct my_struct_type_S {
// lots of fun stuff
callback_type notify_me;
};
answered Jan 3 at 3:19
dbushdbush
104k14109146
1
With the emphasis on the forward declaration part:)
– David C. Rankin
Jan 3 at 3:21
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
add a comment |
You can do this by giving the struct a tag and using a forward declaration of the struct. Then you can use the typedef for the function pointer, and subsequently complete the definition of the struct.
typedef struct my_struct_type_S my_struct_type;
typedef void (*callback_type)(my_struct_type *mst, int whatever);
struct my_struct_type_S {
// lots of fun stuff
callback_type notify_me;
};
answered Jan 3 at 3:19
dbushdbush
104k14109146
You can do this by giving the struct a tag and using a forward declaration of the struct. Then you can use the typedef for the function pointer, and subsequently complete the definition of the struct.
typedef struct my_struct_type_S my_struct_type;
typedef void (*callback_type)(my_struct_type *mst, int whatever);
struct my_struct_type_S {
// lots of fun stuff
callback_type notify_me;
};
answered Jan 3 at 3:19
dbushdbush
104k14109146
edited Jan 3 at 3:21
answered Jan 3 at 3:19
dbushdbush
104k14109146
answered Jan 3 at 3:19
dbushdbush
104k14109146
answered Jan 3 at 3:19
dbushdbush
104k14109146
104k14109146
1
With the emphasis on the forward declaration part:)
– David C. Rankin
Jan 3 at 3:21
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
add a comment |
1
With the emphasis on the forward declaration part:)
– David C. Rankin
Jan 3 at 3:21
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
1
1
With the emphasis on the forward declaration part
:)– David C. Rankin
Jan 3 at 3:21
With the emphasis on the forward declaration part
:)– David C. Rankin
Jan 3 at 3:21
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
Very clean, I like it. Thanks for the info!
– PyroAVR
Jan 5 at 1:41
add a comment |
You need to define the tag of the struct
typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
typedef struct _my_struct_type {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
answered Jan 3 at 3:20
chriptus13chriptus13
244413
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
add a comment |
You need to define the tag of the struct
typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
typedef struct _my_struct_type {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
answered Jan 3 at 3:20
chriptus13chriptus13
244413
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
add a comment |
You need to define the tag of the struct
typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
typedef struct _my_struct_type {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
answered Jan 3 at 3:20
chriptus13chriptus13
244413
You need to define the tag of the struct
typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
typedef struct _my_struct_type {
// lots of fun stuff
callback_type notify_me;
} my_struct_type;
answered Jan 3 at 3:20
chriptus13chriptus13
244413
answered Jan 3 at 3:20
chriptus13chriptus13
244413
answered Jan 3 at 3:20
chriptus13chriptus13
244413
answered Jan 3 at 3:20
chriptus13chriptus13
244413
244413
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
add a comment |
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
When I compile this with 7.2.1 gcc -Wall I get warning: ‘struct _my_struct_type’ declared inside parameter list will not be visible outside of this definition or declaration typedef void (*callback_type)(struct _my_struct_type *mst, int whatever);
– dmuir
Jan 3 at 12:09
add a comment |
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1
Possible duplicate of Structs that refer to each other
– chriptus13
Jan 3 at 3:16