Mercurial > pub > dyncall > dyncall
view dyncallback/dyncallback.3 @ 266:91fd7be165f1
- also testing no flags at all, for asflags rw- detection
author | Tassilo Philipp |
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date | Thu, 25 May 2017 02:13:32 +0200 |
parents | 7cb8a0aaf638 |
children | e2899b4ff713 |
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.\" Copyright (c) 2007-2014 Daniel Adler <dadler AT uni-goettingen DOT de>, .\" Tassilo Philipp <tphilipp AT potion-studios DOT com> .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .Dd $Mdocdate$ .Dt dyncallback 3 .Sh NAME .Nm dyncallback .Nd callback interface of dyncall .Sh SYNOPSIS .In dyncall_callback.h .Ft DCCallback * .Fn dcbNewCallback "const char * signature" "DCCallbackHandler * funcptr" "void * userdata" .Ft void .Fn dcbInitCallback "DCCallback * pcb" "const char * signature" "DCCallbackHandler * funcptr" "void * userdata" .Ft void .Fn dcbFreeCallback "DCCallback * pcb" .Ft void .Fn dcbGetUserData "DCCallback * pcb" .Sh DESCRIPTION The .Nm dyncall library has an interface to create callback objects, that can be passed to functions as callback arguments. In other words, a pointer to the callback object can be "called", directly. The callback handler then allows iterating dynamically over the arguments once called back. .Pp .Fn dcbNewCallback creates a new callback object, where .Ar signature is a signature string describing the function to be called back (see manual or dyncall_signature.h for format). This is needed for .Nm dyncallback to correctly prepare the arguments passed in by the function that calls the callback handler. Note that the handler doesn't return the value specified in the signature, directly, but a signature character, specifying the return value's type. The return value itself is stored where the handler's 3rd parameter points to (see below). .Ar funcptr is a pointer to the .Nm dyncallback callback handler (see below), and .Ar userdata a pointer to arbitrary user data you want to use in the callback handler. Use the returned pointer as callback argument in functions requiring a callback function pointer. .Pp .Fn dcbInitCallback (re)initialize the callback object. .Pp .Fn dcbFreeCallback destroys and frees the callback handler. .Pp .Fn dcbGetUserData returns a pointer to the userdata passed to the callback object on creation or initialization. .Pp Declaration of a dyncallback handler (following function pointer definition in dyncallback/dyncall_callback.h): .Bd -literal -offset indent char cbHandler(DCCallback* cb, DCArgs* args, DCValue* result, void* userdata); .Ed .Pp .Ar cb is a pointer to the DCCallback object in use .Nm result is a pointer to a DCValue object in order to store the callback's return value (output, to be set by handler). Finally, .Ar userdata is a pointer to some user defined data that can be set when creating the callback object. The handler itself returns a signature character (see manual for format) specifying the data type used for .Ar result . .Sh EXAMPLE Let's say, we want to create a callback object and call it. For simplicity, this example will omit passing it as a function pointer to a function (e.g. compar in qsort(), etc.) and demonstrate calling it, directly. First, we need to define our callback handler - the following handler illustrates how to access the passed- in arguments: .Bd -literal -offset indent char cbHandler(DCCallback* cb, DCArgs* args, DCValue* result, void* userdata) { int* ud = (int*)userdata; int arg1 = dcbArgInt (args); float arg2 = dcbArgFloat (args); short arg3 = dcbArgShort (args); double arg4 = dcbArgDouble (args); long long arg5 = dcbArgLongLong(args); // .. do something .. result->s = 1244; return 's'; } .Ed .Pp Note that the return value of the handler is a signature character, not the actual return value, itself. Now, let's call it through a DCCallback object: .Bd -literal -offset indent DCCallback* cb; short result = 0; int userdata = 1337; cb = dcbNewCallback("ifsdl)s", &cbHandler, &userdata); result = ((short(*)(int, float, short, double, long long))cb) (123, 23.f, 3, 1.82, 9909ll); dcbFreeCallback(cb); .Ed .Sh CONFORMING TO The dyncallback library needs at least a c99 compiler with additional support for anonymous structs/unions (which were introduced officially in c11). Given that those are generally supported by pretty much all major c99 conforming compilers (as default extension), it should build fine with a c99 toolchain. Strictly speaking, dyncall conforms to c11, though. .Ed .Sh SEE ALSO .Xr dyncall 3 , .Xr dynload 3 and the dyncall manual (available in HTML and PDF format) for more information. .Sh AUTHORS .An "Daniel Adler" Aq dadler@uni-goettingen.de .An "Tassilo Philipp" Aq tphilipp@potion-studios.com