Names, Scopes, and Bindings Names, Scopes, and ... - Lrde - Epita

Bindings
Symbol Tables
Complications
Binding Time: the moving IN
Names
Scopes
Binding Time
Bindings
Symbol Tables
Complications
Names
Scopes
Binding Time
Dynamic Binding: virtual in C++
Roughly, flexibility and efficiency
are mutually exclusive
depend on binding time.
The Moving In
binding-time
early ---------------------------------> late
INflexibility
efficiency
flexibility
INefficiency
Dynamic dispatch is roughly runtime overloading.
Dynamic Dispatch in C++
struct Shape
{
virtual void draw () const = 0;
};
struct Square : public Shape
{
virtual void draw () const {};
};
struct Circle : public Shape
{
virtual void draw () const {};
};
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Bindings
Symbol Tables
Complications
Names
Scopes
Binding Time
Dynamic Binding: virtual in C++
Bindings
Symbol Tables
Complications
Late Code Binding: eval
Names
Scopes
Binding Time
Dynamic Dispatch in C++
#include
#include "shapes.hh"
typedef std::list shapes_type;
int main ()
{
shapes_type ss;
ss.push_back (new Circle);
ss.push_back (new Square);
}
for (shapes_type::iterator i = ss.begin ();
i != ss.end (); ++i)
// Inclusion polymorphism.
(*i)->draw ();
Most interpreted
languages support
eval (explicit or
not): runtime code
evaluation.
Enables language
extensions.
try/catch in Perl
sub try (&@) {
my ($try, $catch) = @_;
eval { &$try }; # Explicit eval.
if ($@) {
local $_ = $@;
&$catch;
}
}
sub catch (&) {
$_[0];
# implicit eval.
}
try {
die "phooey";
} catch {
/phooey/ and print "unphooey\n";
};
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