overloading

display, functions and operators overloading capabilities

Description

In scilab, variable display, functions and operators may be defined for new objects using functions (scilab coded or primitives).

:Display The display of new objects defined by tlist structure may

be overloaded (the default display is similar to list‘s one). The overloading function must have no output argument a single input argument. It’s name is formed as follow %<tlist_type>_p where %<tlist_type> stands for the first entry of the tlist type component truncated to the first 9 characters.

: :Operators Each operator which is not defined for given operands

type may be defined. The overloading function must have a single output argument and one or two inputs according to the number of operands. The function name is formed as follow:

:

for binary operators: %<first_operand_type>_<op_code>_<second_operand_type>

for unary operators: %<operand_type>_<op_code>

extraction and insertion operators which are n-nary operators are described below.

Be careful, only the types registered by the typename function can be used in an overloading macros

<operand_type>, <first_operand_type>, <second_operand_type> are sequence of characters associated with each data type as described in the following table: data type char code typeof comments double matrix s constant polynomial matrix p polynomial boolean matrix b boolean sparse matrix sp sparse boolean sparse matrix spb boolean sparse Matlab sparse matrix msp Matlab sparse integer matrix i int8, int16,int32, uint8, uint16, uint32 string matrix c string handle h handle compiled function fptr fptr script function mc function library f library list l list tlist tlist type tlist type the first string in the first tlist entry mlist mlist type mlist type the first string in the first mlist entry hypermatrix hm hypermat pointer ptr pointer cell ce ce structure st st rational r rational linear state space lss state-space implicit polynom ip size implicit 1:1:$ <op_code> is a single character associated with each operator as described in the following table: op char code ‘ t + a - s * m / r ` l `^ p .* x ./ d .` q `.*. k ./. y .. z : b *. u /. v . w [a,b] c [a;b] f () extraction e () insertion i == o <> n | g & h .^ j .’ 0 < 1 > 2 <= 3 >= 4 ~ 5 iext 6 The overloading function for extraction syntax b= a(i1, ..., in) has the following calling sequence: b = %<type_of_a>_e_(i1, ..., in, a)

and the syntax [x1, .., xm] = a(i1, ..., in) has the following calling sequence: [x1, .., xm] = %<type_of_a>_e_(i1, ..., in, a)

The overloading function associated to the insertion syntax a(i1, ..., in) = b has the following calling sequence: a = %<type_of_b>_i_<type_of_a>(i1, ..., in, b, a) .

The 6 char code may be used for some complex insertion algorithm like x.b(2) = 33 where b field is not defined in the structure x. The insertion is automatically decomposed into temp = x.b; temp(2) = 33; x.b = temp. The 6 char code is used for the first step of this algorithm. The 6 overloading function is very similar to the e‘s one.

:Functions : Some basic primitive function may also be overloaded for

new data type. When such a function is undefined for a particular data types the function %<type_of_an_argument>_<function_name> is called. User may add in this called function the definition associated with the input data types.

:

Examples

//DISPLAY
      function []=%tab_p(l)
      `disp`_([[' '; l(3)] [l(2); `string`_(l(4))]])
      endfunction

      `tlist`_('tab', ['a', 'b'], ['x'; 'y'], `rand`_(2, 2))

//OPERATOR
      function x=%c_a_s(a, b)
      x = a + `string`_(b);
      endfunction

      's' + 1

//FUNCTION
      function x=%c_sin(a)
      x = 'sin(' + a + ')'
      endfunction

      `sin`_('2 * x')

See Also

• tlist Scilab object and typed list definition.
• disp displays variables
• symbols scilab operator names
• typeof object type
• `type`_ Returns the type of a variable
• `type`_ associates a name to variable type