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Pile

Pile aims to build an elegant library and scripting language for small devices.

It has several components including pile class, pile library, pile runtime and pile intepreter.

Pile Class

Pile uses C macro and struct to implement classes.

Here's an example:

// test_class.h
#include "pile_class.h"
#include "pile_types.h"
#define PILE_CLASS_SHORTCUTS true
class(test_class)
{
    pile_int_t a;

    pile_int_t def_fn(test_class, get_a);
    def_destruct(test_class);
};

// test_class.c
pile_int_t impl_fn(test_class, get_a)
{
    return self->a;
}
impl_construct(test_class, pile_int_t a)
{
    self->a = a;
    _assgin(test_class, get_a);
}
impl_default_destruct(test_class);

// main.c
#include <stdio.h>
#include "test_class.h"

int main() {
    new(test_class, ins, 10);
    printf("%d\r\n", ins->get_a(ins));
    ins->a = 1000;
    printf("%d\r\n", call(ins, get_a));
    del(ins);
    renew(test_class, ins, 200);
    printf("%d\r\n", ins->get_a(ins));
    del(ins);
    return 0;
}

Class Shortcuts

The macros have shortcuts when PILE_CLASS_SHORTCUTS is defined.

You can disable that if the shortcuts cause name conflicts.

Shortcut Origin
class PILE_CLASS
new PILE_NEW
del PILE_DEL
impl_fn PILE_CLASS_METHOD
impl_construct PILE_CLASS_CONSTRUCTOR
impl_destruct PILE_CLASS_DESTRUCTOR
impl_default_destruct PILE_CLASS_DESTRUCTOR_DEFAULT
_assign PILE_ASSIGN_METHOD
def_fn PILE_DEFINE_METHOD
def_destruct PILE_DEFINE_DESTRUCT
call PILE_CALL

In the document, we will use shortcuts to tell.

Define a class

class(test_class)
{
    pile_int_t a;

    void def_fn(test_class, set_a, pile_int_t a);

    def_destruct(test_class);
};

In the code above, we define a class named test_class.

To define a class, we need to use macro class or PILE_CLASS. It receives an argument as the class name. Then a struct body need to be followed.

Note: after the brackets the semicolon(;) cannot be missed.

Because of the limits of C language, pile doesn't support private atrributes. The properties can be defined in normal struct way, like: pile_str_t str;.

When defining class methods, we use def_fn or PILE_DEFINE_METHOD macros. The macro receives its first parameter as the class name, and the second as method name. The return type should be defined before calling the macro, and the parameter list should start at the third macro parameter, separated by commas.

Note the constructor should not be defined in the class definition. But the destructor must be defined using def_destruct or PILE_DEFINE_DESTRUCT macro. The macro receives its first parameter as the class name and no other parameters should be followed.

The following types will be defined as in the example:

  • struct test_class: The original struct type
  • test_class_t: Orignal type defined using typedef
  • test_class_ptr_t: Pointer to the original type (instance type)

Implement a method

Note: constructors and destructors should be defined using another macro, which will be described in the next section.

When implementing a method, macro impl_fn or PILE_CLASS_METHOD should be used.

void impl_fn(test_class, set_a, pile_int_t a)
{
    self->a = a;
}

The return type should be defined before calling the macro.

The first parameter is the class name while the second is the method name.

The following parameters are argument list of the method.

Inside the function body we can use self to access the instance.

Implementing a destructor

In a destructor, a class can free the resources it uses.

Use impl_destruct or PILE_CLASS_DESTRUCTOR to implement one.

Example:

impl_destruct(test_class)
{
    PILE_FREE(self->data);
}

When a class does nothing in a destructor, you can use impl_default_destruct.

Example:

impl_default_destruct(test_class);

Implement a constructor

A constructor need to do two things:

  1. Init the properties
  2. Assign methods

You can use impl_construct or PILE_CLASS_CONSTRUCT macros to implement.

The first parameter is class name, and it can receive a parameter list.

impl_construct(test_class, pile_int_t a)
{
    _assign(test_class, set_a);

    self->set_a(a);
}

The _assign or PILE_ASSIGN macro can automatically assign a method to a class.

All the methods need to be assigned in the constructor,

The macro receives two parameters, where the first one is the class name and the second one is the method name.

Creating a new instance

You can use new or PILE_NEW macros to create a new instance.

Example:

new(test_class, ins, 123);

The first parameter is the class name, while the second is the variable name. The following parameters will be passed to the constructor. Then you can use ins to access the instance.

The above code will create a new variable with type test_class_ptr_t.

If you have a variable typed that already available, you can use renew or PILE_RENEW macro to re-initialize it.

Example:

test_class_ptr_t ins;
renew(test_class, ins, 123);

Deleting a instance

Use del or PILE_DEL macros.

Example:

del(ins);

The parameter is the variable name of the instance.

Calling a method

You can use ins->method_name(ins, 123); to call a method.

Note the first parameter should pass the variable again.

If you use call or PILE_CALL macro, then you don't need to pass itself again. It looks like:

call(test_cass, set_a, 100);

The first parameter is the class name, while the second one is the method name.

Shortcuts

pcert = pile_container_t

pvcoer = PILE_VALUE_CONTAINER