Function load_as_q_function

pub fn load_as_q_function(func: *const V, n: J) -> K

Load C function as a q function (K object).

Parameters

• func: A function takes a C function that would take n K objects as arguments and returns a K object.
• n: The number of arguments for the function.

Example

use kdb_c_api::*;
 
#[derive(Clone, Debug)]
struct Planet{
  name: String,
  population: i64,
  water: bool
}
 
impl Planet{
  /// Constructor of `Planet`.
  fn new(name: &str, population: i64, water: bool) -> Self{
    Planet{
      name: name.to_string(),
      population: population,
      water: water
    }
  }
 
  /// Description of the planet.
  fn description(&self)->String{
    let mut desc=format!("The planet {} is a beautiful planet where {} people reside.", self.name, self.population);
    if self.water{
      desc+=" Furthermore water is flowing on the surface of it.";
    }
    desc
  }
}
 
/// Example of `set_type`.
#[no_mangle]
pub extern "C" fn eden(_: K) -> K{
  let earth=Planet::new("earth", 7500_000_000, true);
  let foreign=new_simple_list(qtype::COMPOUND, 2);
  let foreign_slice=foreign.as_mut_slice::<K>();
  foreign_slice[0]=drop_q_object as K;
  foreign_slice[1]=Box::into_raw(Box::new(earth)) as K;
  // Set as foreign object.
  foreign.set_type(qtype::FOREIGN);
  foreign
}
 
extern "C" fn invade(planet: K, action: K) -> K{
  let obj=planet.as_mut_slice::<K>()[1] as *const Planet;
  println!("{:?}", unsafe{obj.as_ref()}.unwrap());
  let mut desc=unsafe{obj.as_ref()}.unwrap().description();
  if action.get_bool().unwrap(){
    desc+=" You shall not curse what God blessed.";
  }
  else{
    desc+=" I perceived I could find favor of God by blessing them.";
  }
  new_string(&desc)
}
 
/// Example of `load_as_q_function`.
#[no_mangle]
pub extern "C" fn probe(planet: K)->K{
  // Return monadic function
  unsafe{native::k(0, str_to_S!("{[func; planet] func[planet]}"), load_as_q_function(invade as *const V, 2), planet, KNULL)}
}

q)eden: libc_api_example 2: (`eden; 1);
q)earth: eden[]
q)type earth
112h
q)probe: libc_api_example 2: (`probe; 1);
q)invade: probe[earth];
q)\c 25 200
q)invade 1b
"The planet earth is a beautiful planet where 7500000000 people reside. Furthermore water is flowing on the surface of it. You shall not curse what God blessed."