Re: An overview of the Parrot interpreter

[Nathan Torkington]

Sam Tregar writes:
> > If our PMC is a string and has a vtable which implements Perl-like
> > string operations, this will return the length of the string. If, on the
> > other hand, the PMC is an array, we might get back the number of
> > elements in the array. (If that's what we want it to do.)
> 
> Ok, so one example of a PMC is a Perl string...

If you grok vtables, think of a PMC as the thing a vtable hangs off.

Another way to think of it is that a PMC is an object.  To the outside
(the interpreter that is manipulating data values) its contents are
opaque.  All you can do is call methods (vtable entries) on it.

So if you have an object/PMC that implements a string, the "length"
method/vtable-entry will return the length of the string.  An
object/PMC that implements an array, the "length" method/vtable-entry
will return the number of things in the array.

Nat