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comparison dyncallback/dyncallback.3 @ 96:95f67e67feb0

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- updated dyncallback.3, blurb about handler's retval signature character was outdated
author cslag
date Sat, 04 Jun 2016 19:32:21 +0200
parents dfde5035d410
children 7cb8a0aaf638
comparison
equal deleted inserted replaced
95:9e99918065e6 96:95f67e67feb0
37 dynamically over the arguments once called back. 37 dynamically over the arguments once called back.
38 .Pp 38 .Pp
39 .Fn dcbNewCallback 39 .Fn dcbNewCallback
40 creates a new callback object, where 40 creates a new callback object, where
41 .Ar signature 41 .Ar signature
42 is a signature string describing the function to be called back (see manual for 42 is a signature string describing the function to be called back (see manual or
43 format). This is needed for 43 dyncall_signature.h for format). This is needed for
44 .Nm 44 .Nm
45 dyncallback to correctly prepare the arguments passed in by the function that 45 dyncallback to correctly prepare the arguments passed in by the function that
46 calls the callback handler. Note that the handler doesn't return the value 46 calls the callback handler. Note that the handler doesn't return the value
47 specified in the signature, directly, but simply 'i' or 'f' depending on whether 47 specified in the signature, directly, but a signature character, specifying the
48 it is a integral or floating point type. The return value itself is stored 48 return value's type.
49 where the handler's 3rd parameter points to (see example). 49 The return value itself is stored where the handler's
50 3rd parameter points to (see below).
50 .Ar funcptr 51 .Ar funcptr
51 is a pointer to the 52 is a pointer to the
52 .Nm 53 .Nm
53 dyncallback callback handler (see below), and 54 dyncallback callback handler (see below), and
54 .Ar userdata 55 .Ar userdata
104 long long arg5 = dcbArgLongLong(args); 105 long long arg5 = dcbArgLongLong(args);
105 106
106 // .. do something .. 107 // .. do something ..
107 108
108 result->s = 1244; 109 result->s = 1244;
109 return 'i'; 110 return 's';
110 } 111 }
111 .Ed 112 .Ed
112 .Pp 113 .Pp
113 Note that the return value of the handler is a signature character, not the 114 Note that the return value of the handler is a signature character, not the
114 actual return value, itself, and note that the actual return value is of type 115 actual return value, itself.
115 short.
116 Now, let's call it through a DCCallback object: 116 Now, let's call it through a DCCallback object:
117 .Bd -literal -offset indent 117 .Bd -literal -offset indent
118 DCCallback* cb; 118 DCCallback* cb;
119 short result = 0; 119 short result = 0;
120 int userdata = 1337; 120 int userdata = 1337;