overloading — display, functions and operators overloading capabilities
In scilab, variable display, functions and operators may be defined for new objects using functions (scilab coded or primitives).
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.
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 |
| size implicit polynomial | ip |
Matlab sparse matrix | msp |
| mlist | mlist_type |
pointer | ptr |
<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 |
| 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.
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.