mg_type  MGVTBL              Type of magic
    -------  ------              ----------------------------
    \0       vtbl_sv             Special scalar variable
    A        vtbl_amagic         %OVERLOAD hash
    a        vtbl_amagicelem     %OVERLOAD hash element
    c        (none)              Holds overload table (AMT) on stash
    B        vtbl_bm             Boyer-Moore (fast string search)
    D        vtbl_regdata        Regex match position data (@+ and @- 
+vars)
    d        vtbl_regdatum       Regex match position data element
    E        vtbl_env            %ENV hash
    e        vtbl_envelem        %ENV hash element
    f        vtbl_fm             Formline ('compiled' format)
    g        vtbl_mglob          m//g target / study()ed string
    I        vtbl_isa            @ISA array
    i        vtbl_isaelem        @ISA array element
    k        vtbl_nkeys          scalar(keys()) lvalue
    L        (none)              Debugger %_<filename 
    l        vtbl_dbline         Debugger %_<filename element
    o        vtbl_collxfrm       Locale transformation
    P        vtbl_pack           Tied array or hash
    p        vtbl_packelem       Tied array or hash element
    q        vtbl_packelem       Tied scalar or handle
    S        vtbl_sig            %SIG hash
    s        vtbl_sigelem        %SIG hash element
    t        vtbl_taint          Taintedness
    U        vtbl_uvar           Available for use by extensions
    v        vtbl_vec            vec() lvalue
    x        vtbl_substr         substr() lvalue
    y        vtbl_defelem        Shadow "foreach" iterator variable /
                                  smart parameter vivification
    *        vtbl_glob           GV (typeglob)
    #        vtbl_arylen         Array length ($#ary)
    .        vtbl_pos            pos() lvalue
    ~        (none)              Available for use by extensions
[download]

I agree it's too limited to be called Magic::Attach. That would be a good name for a helper module used to implement such a thing, something you wish you had instead of having to write in XS.

The use of the ~ table is meerly an implementation detail. What the module does is attach named attributes to a value at run time. It should be named for its public interface and purpose, not for its implementation details. (Save that name for a concrete implementation when the same interface is implemented multiple ways based on the situation).

This concept is what Perl 6 calls "Properties", and LISP also calls it properties. It's different from the existing Perl attributes or attribs.

—John

If I add the callback functionality, perhaps it will be worthy of the name. But even then I think the name should be somewhat generic because it is not intended to be a property or attribute, simply the binding of pieces of data. What you do with it on the other hand...

While I understand the "magic" part is simply an implementation detail, it might be worth having simply for the fact that when something goes wrong, something along these lines is bound to break in strange ways where most people would never think to look.

BTW, What is the best place to get up to speed on Perl 6. I read the exgenesis and apocalypses but I'm sure much has changed. Any good overviews of the current state?

-Lee

"To be civilized is to deny one's nature."

Hm. The on the one hand, yes, from this table. On the other hand, it feels like it should be possible to make a half-tied variable, which invokes a perl sub when stored into, but has no overhead (and does nothing special) when gotten from (or vice-versa). The docs confuse me.

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Warning: Unless otherwise stated, code is untested. Do not use without understanding. Code is posted in the hopes it is useful, but without warranty. All copyrights are relinquished into the public domain unless otherwise stated. I am not an angel. I am capable of error, and err on a fairly regular basis. If I made a mistake, please let me know (such as by replying to this node).