function table

In computer science, a dispatch table is a table of pointers or memory addresses to functions or methods. Use of such a table is a common technique when implementing late binding in object-oriented programming.

Perl implementation

The following shows one way to implement a dispatch table in Perl, using a hash to store references to code (also known as function pointers).

# Define the table using one anonymous code-ref and one named code-ref
my %dispatch = (
"-h" => sub ,
"-g" => \&say_goodbye
);

sub say_goodbye

# Fetch the code ref from the table, and invoke it
my $sub = $dispatch;
print $sub ? $sub->() : "unknown argument\n";

Running this Perl program as perl greet -h will produce "hello", and running it as perl greet -g will produce "goodbye".

JavaScript implementation

Following is a demo of implementing dispatch table in JavaScript:

var thingsWeCanDo = ;

var doSomething = function(doWhat)

Virtual method tables

In object-oriented programming languages that support virtual methods, the compiler will automatically create a dispatch table for each object of a class containing virtual methods. This table is called a virtual method table or ''vtable'', and every call to a virtual method is dispatched through the vtable.

See also

* Branch table

References

* Diomidis Spinellis (2003). '' Code Reading: The Open Source Perspective''. Boston, MA: Addison-Wesley. {{ISBN, 0-201-79940-5

Method (computer programming)
Articles with example Perl code