Scilab Home page | Wiki | Bug tracker | Forge | Mailing list archives | ATOMS | File exchange
Please login or create an account
Change language to: English - Português - Русский - 日本語

Please note that the recommended version of Scilab is 6.0.0. This page might be outdated.
See the recommended documentation of this function

Aide de Scilab >> Fonctions avancées > overloading

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 and 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 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
            var = tlist('tab', ['a', 'b'], ['x'; 'y'], rand(2, 2)) // the type of var is 'tab'
            
            typeof(var)
            
            function []=%tab_p(l)
            disp([[' '; l(3)] [l(2); string(l(4))]])
            endfunction
            
            var // after overloading
//OPERATOR
            's' + 1 // it is impossible to add a number to a string
            
            function x=%c_a_s(a, b)
            x = a + string(b);
            endfunction
            
            's' + 1 // after overloading
//FUNCTION
            sin('2 * x') // the sin function does not work with a string
            
            function x=%c_sin(a)
            x = 'sin(' + a + ')'
            endfunction
            
            sin('2 * x') // after overloading

See Also

  • tlist — Objet Scilab. Définition d'une liste typée
  • disp — displays variables
  • symbols — opérateurs de Scilab
  • typeof — object type
  • type — Retourne le type d'une variable
  • typename — associe un nom à un type de variable
Scilab Enterprises
Copyright (c) 2011-2017 (Scilab Enterprises)
Copyright (c) 1989-2012 (INRIA)
Copyright (c) 1989-2007 (ENPC)
with contributors
Last updated:
Thu Oct 02 13:54:44 CEST 2014