68 lines
2.1 KiB
Markdown
68 lines
2.1 KiB
Markdown
## Binding C Functions {#c_functions}
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Whether you're embedding Kuroko in an application or writing an extension module, binding a C function is something you'll want to do.
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### The Easy Way
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```c
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#include <kuroko/kuroko.h>
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#include <kuroko/vm.h>
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#include <kuroko/util.h>
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KRK_FUNC(myfunction,{
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FUNCTION_TAKES_EXACTLY(1);
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CHECK_ARG(0,int,krk_integer_type,myarg);
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return INTEGER_VAL(myarg*myarg);
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})
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int main(int argc, char *argv[]) {
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krk_initVM(0);
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BIND_FUNC(vm.builtins, myfunction);
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krk_startModule("__main__");
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krk_interpret("print(myfunction(42))","<stdin>");
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krk_freeVM();
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return 0;
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}
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```
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This demo uses the utility macros provided in `<kuroko/util.h>` to easily create a function with argument checking and bind it to the builtin namespace.
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`KRK_FUNC()` takes care of the function signature, function naming, and default return value of `None`.
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`FUNCTION_TAKES_EXACTLY()` provides simple argument count validation. `FUNCTION_TAKES_AT_LEAST()` and `FUNCTION_TAKES_AT_MOST()` are also available.
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`CHECK_ARG()` validates the type of arguments passed to the function and unboxes them to C types.
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`INTEGER_VAL()` converts a C integer to a Kuroko `int` value.
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`BIND_FUNC()` binds the function to a namespace table.
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### The Hard Way
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While the macros above provide a convenient way to bind functions, they are just wrappers around lower-level functionality of the API.
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```c
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#include <kuroko/kuroko.h>
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#include <kuroko/vm.h>
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static KrkValue myfunction(int argc, KrkValue argv[], int hasKw) {
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int myarg;
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if (argc != 1) return krk_runtimeError(vm.exceptions->argumentError, "myfunction() expects exactly 1 argument, %d given", argc);
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if (!IS_INTEGER(argv[0])) return krk_runtimeError(vm.exceptions->typeError, "expected int, not '%s'", krk_typeName(argv[0]));
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myarg = AS_INTEGER(argv[0]);
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return INTEGER_VAL(myarg*myarg);
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}
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int main(int argc, char *argv[]) {
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krk_initVM(0);
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krk_defineNative(&vm.builtins->fields, "myfunction", myfunction);
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krk_startModule("__main__");
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krk_interpret("print(myfunction(42))", "<stdin>");
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krk_freeVM();
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return 0;
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}
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```
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