Hi,
This has very little practical value but I wonder if it is possible to hack
Perl into using a pseudo object-oriented style for the built-in functions
that deal with arrays. That is, in stead of saying
reverse @array;
you could say
$array->reverse();
rather than doing
sort &\func, @myArray;
you would have:
$foo->sort(\&func);
And so on. More formally, for all sub-routines in the package %CORE:: that
pass one array by reference and take zero or more other arguments, make it
an equivalent method call where the array is the object on which to operate
but otherwise the parameter order is intact.
I'd been wishing for this kind of "silly" feature when experimenting in C
but didn't come up with anything useful based on macroes at least. THen I
saw an app-specific, obscure scripting language called FraggleScript which
actually had the basic idea as a generic language feature, though it didn't
support OOP at all. That is:
param1.function(...)
being exactly equivalent to
function(param1, ...)
My first thought in Perl, though, was to attempt source filtering. But it is
all too easy to filter half-heartedly and end-up destroying some language
features in the process i.e. not allowing chained method calls, if Perl
supports them. I must confess I only toyed with the idea without even trying
the implementation just yet.
My second port of call was to make a minimal object, a blessed array, and
use its autoload function, err method, to forward the method calls to the
built-ins. that is, determine the function name, get its prototype,
re-arrange the parameter list and call. I've succesfully used autoloading
before, to create a logarithm function which takes the base in the function
name e.g. log2(argument).
I went and read about symbol tables and such and again was awe struck by how
simple Perl makes things. Coming from a Java background, reflection still
feels sort of magical and I was happy to discover that Perl treats even
symbol tables as hashes. Again, lack of abstraction feels wonderful when
programming in the small.
Anyway, I found the package CORE:: in all caps and it had a member GLOBAL::.
Then I tried listing the keys of %CORE::GLOBAL:: but got neither data nor
functions out. I'm certain that there's a perfectly sensible explanation for
this but I haven't figured out what that might be. Maybe they want to
protect you from overriding the built-ins, which would be a very unperlish
thing to do, in my view at least. Compare to the ease with which you can
change almost everything in Ruby, unless I'm much mistaken.
Well, not being able to iterate the built-ins hasn't been my only problem. I
tested the prototype function and it seems many of the built-ins are highly
magical, too. While most of the string functions appear to have prototypes,
many that handle array references and blocks, such as grep, map and sort,
cannot be represented as a prototype at all, I think.
If all else fails, I reckon I could mmirror the built-ins in my class and
arrange all the parameters for the functions manually. But creating one
method per built-in is certainly not the lazy way and it wont' automatically
scale should new Perl versions come out. I doubt they'll be changing the
built-ins any time soon but the manual method still seems the least
interesting to me.
Mind you this Perl hack is not because I'm an OOP advocate or want to
achieve something useful. Rather, I'd like to know Perl better and have some
fun in the process.
So, are there any strategies I might have overlooked or is this pseudo-OOP
syntax simply something unreachable (without doing func specific work)?
Also, any tips or general help would be appreciated as usual.
PS: I reckon it is ok to ask this kind of question, even though this is a
Win32 list.
--
With kind regards Veli-Pekka Tätilä ([EMAIL PROTECTED])
Accessibility, game music, synthesizers and programming:
http://www.student.oulu.fi/~vtatila/
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