|GNU Octave Manual Version 3|
by John W. Eaton, David Bateman, Søren Hauberg
Paperback (6"x9"), 568 pages
RRP £24.95 ($39.95)
11.7.3 Overloading and Autoloading
dispatch function can be used to alias one function name to
another. It can be used to alias all calls to a particular function name
to another function, or the alias can be limited to only a particular
variable type. Consider the example
function y = spsin (x) printf ("Calling spsin\n"); fflush(stdout); y = spfun ("sin", x); endfunction dispatch ("sin", "spsin", "sparse matrix"); y0 = sin(eye(3)); y1 = sin(speye(3));
which aliases the user-defined function
sin, but only for real sparse
matrices. Note that the builtin
sin already correctly treats
sparse matrices and so this example is only illustrative.
- Loadable Function: dispatch (f, r, type)
Replace the function f with a dispatch so that function r is called when f is called with the first argument of the named type. If the type is any then call r if no other type matches. The original function f is accessible using
builtin (f, ...).
If r is omitted, clear dispatch function associated with type.
If both r and type are omitted, list dispatch functions for f.
See also builtin
- Loadable Function: [...] builtin (f, ...)
- Call the base function f even if f is overloaded to
some other function for the given type signature.
See also dispatch
A single dynamically linked file might define several functions. However, as Octave searches for functions based on the functions filename, Octave needs a manner in which to find each of the functions in the dynamically linked file. On operating systems that support symbolic links, it is possible to create a symbolic link to the original file for each of the functions which it contains.
However, there is at least one well known operating system that doesn't
support symbolic links. Making copies of the original file for each of
the functions is undesirable as it increases the
amount of disk space used by Octave. Instead Octave supplies the
autoload function, that permits the user to define in which
file a certain function will be found.
- Built-in Function: autoload (function, file)
- Define function to autoload from file.
The second argument, file, should be an absolute file name or a file name in the same directory as the function or script from which the autoload command was run. file should not depend on the Octave load path.
Normally, calls to
autoloadappear in PKG_ADD script files that are evaluated when a directory is added to the Octave's load path. To avoid having to hardcode directory names in file, if file is in the same directory as the PKG_ADD script then
autoload ("foo", "bar.oct");
will load the function
foofrom the file
bar.oct. The above when
bar.octis not in the same directory or uses like
autoload ("foo", file_in_loadpath ("bar.oct"))
are strongly discouraged, as their behavior might be unpredictable.
With no arguments, return a structure containing the current autoload map.
See also PKG_ADD
|ISBN 095461206X||GNU Octave Manual Version 3||See the print edition|