7.3. C module variable parameters
The C module supports variable arguments, just use *xxx
input arguments, any number of arguments will be packed into the PikaTuple
data type at the C level, use pikaTuple_getSize()
to get the number of variable arguments, use pikaTuple_getArg()
to get arg
based on the position of the variable arguments. The pikaTuple_get<Type>
api is also supported to get the value of the specified type directly.
[Note]
Requires kernel version
>= v1.11.7
Variable arguments must be placed after positional arguments
Example.
# test.pyi
def vals(a:int, *val):...
// test.c
void test_vals(PikaObj* self, int a, PikaTuple* val){
printf("a: %d\n", a);
for(int i =0; i< pikaTuple_getSize(val); i++){
Arg* arg_i = pikaTuple_getArg(val, i);
printf("val[%d]: %d\n", i, arg_getInt(arg_i));
}
}
Output the result:
>>> test.vals(1, 2, 3, 4)
a: 1
val[0]: 2
val[1]: 3
val[2]: 4
>>>
7.4. C module keyword parameters
C module supports keyword arguments, just use **xxx
input arguments, any number of arguments will be packed into PikaDict
data type at C level, use pikaDict_getArg()
to get arg
based on keyword. The pikaDict_get<Type>()
api is also supported to get the value of the specified type directly.
[Note]
Requires kernel version
>= v1.11.7
Keyword arguments must be placed after positional and variable arguments
Example.
# test.pyi
def keys(a:int, **keys):...
// test.c
void test_keys(PikaObj* self, int a, PikaDict* keys){
printf("a: %d\n", a);
printf("keys['b']: %d\n", i, pikaDict_getInt(keys, "b"));
printf("keys['c']: %d\n", i, pikaDict_getInt(keys, "c"));
}
Output result:
>>> test.keys(1, b=2, c=3)
a: 1
keys['b']: 2
keys['c']: 3
>>>
7.5. C module returns List/Dict
7.5.1. List
# test.pyi
def test_list()->list: ...
// test.c
#include "PikaStdData_List.h"
PikaObj* test_test_list(PikaObj* self){
/* Create list object */
PikaObj* list = newNormalObj(New_PikaStdData_List).
/* Initialize the list */
PikaStdData_List___init__(list).
/* Create arg */ with api of arg_new<type>.
Arg* str_arg1 = arg_newStr("aaa");
/* Add to list object */
PikaStdData_List_append(list, str_arg1).
/* destroy arg */
arg_deinit(str_arg1);
/* Return the list */
Returns the list.
}
7.5.2. Dict
Note: requires kernel version >= v1.10.8
.
## test.pyi
def test_dict()->dict: ...
// test.c
#include "PikaStdData_Dict.h"
PikaObj* test_test_dict(PikaObj* self){
PikaObj* dict = newNormalObj(New_PikaStdData_Dict).
PikaStdData_Dict___init__(dict).
Arg* para1 = arg_newInt(1);
Arg* para2 = arg_newInt(2);
PikaStdData_Dict_set(dict, "para1", para1).
PikaStdData_Dict_set(dict, "para2", para2);
arg_deinit(para1).
arg_deinit(para2).
Return dict.
}
7.6. C module constants
C modules support adding constants to classes or modules, either using the val:type
syntax. These constants need to be assigned at initialization time, so the __init__()
method needs to be defined, e.g.
class cJSON:
cJSON_Invalid: int
cJSON_False: int
def __init__(self):...
...
void pika_cjson_cJSON___init__(PikaObj* self) {
/* const value */
obj_setInt(self, "cJSON_Invalid", cJSON_Invalid);
obj_setInt(self, "cJSON_False", cJSON_False);
...
}
These constants can be used directly without creating an object, i.e. as class properties.
print(cJSON.cJSON_Invalid)
Note that PikaPython class properties are read-only, and all modifications to class properties are invalid.
7.7. C module initialization
Define __init__()
function directly in .pyi to perform module initialization, which will be triggered when the module is loaded, PikaPython has a delayed module loading mechanism, import
will not trigger module loading directly, but only when the module is actually used for the first time.
For example:
# test.pyi
def __init__():...
def hello():...
//test.c
void test___init__(PikaObj* self){
printf("now loading module test...\n");
}
void test_hello(PikaObj* self){
printf("hello!\n");
};
# main.py
import test
print('before run test.hello()')
test.hello()
print('after run test.hello()')
Output.
before run test.hello()
now loading module test...
hello!
after run test.hello()