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.

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.

<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	data type	char code
constant	s	boolean	b
string	c	library	f
function pointer	fptr	handle	h
integer	i	list	l
function	m	compiled function	mc
polynomial	p	sparse	sp
boolean sparse	spb	tlist	tlist_type

<op_code> is a single character associated with each operator as described in the following table:

op	char code	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
~	5	.'	0
<	1	>	2
<=	3	>=	4

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_a>_i_<type_of_b>(i1,...,in,b,a).

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
deff('[]=%tab_p(l)','disp([['' '';l(3)] [l(2);string(l(4))]])')
tlist('tab',['a','b'],['x';'y'],rand(2,2))

//OPERATOR
deff('x=%c_a_s(a,b)','x=a+string(b)')
's'+1

//FUNCTION
deff('x=%c_sin(a)','x=''sin(''+a+'')''')
sin('2*x')
   

See Also

tlist  disp  symbols