in reply to Dynamically Creating (and Calling) Object Methods

Almost there! 

$myDB->{method1}->();

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Note that you are adding these methods per *instance*, not to the whole class -- this is a technique used in prototype OOP. If you wanted to dynamically augment your class, the hash you need to edit is actually the BigDB package's symbol table.

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Re^2: Dynamically Creating (and Calling) Object Methods
by zaven (Sexton) on Jan 07, 2007 at 09:16 UTC
    Thanks for the reply. That does make sense. After some googling I tried this approach in BigDB::new()... 
         # $cmd = "method1"
     eval {
                no strict 'refs';
                *{'BigDB\::$cmd'} = makeCommandSub($CMDS->{$cmd});
            } or die "Can't modify the symbol table: $!";

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    ...but this does not seem to result in a usable $myDB->method1() as I would like. ("Cannot locate method "method1" via package BigDB....")

    So next I tried hard-coding the new symbol name like so: 

    *BigDB::method1 = makeCommandSub(...);

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    and that works! So I just need to know how to use a string as part of the symbol reference. More clues? :-)
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      First, unrelated to your main task: you don't need to say eval {...} or die $!, for several reasons. The first is that if it throws an exception, you can probably use the original exception :) Second, the or there is dangerous unless makeCommandsSub is guaranteed to return a true value; the valuation of an eval is (like any other block of Perl 5) its last evaluated thing. So 
      eval { 0 } or die "this dies, but not because of an exception in the i
+nner block!";

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      Finally, $! is wrong in this case, you need $@ for the exception.

      But to your real question:

      You said 'BigDB\::$cmd'. But because of the single quotes, this creates literally a '$cmd' package in BigDB's symbol table! (Check by printing keys %BigDB::.) The correct code is 

      *{"BigDB::$cmd"} = ...

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      You probably got the backslash from code that used a variable containing the caller, where it's needed to make Perl not think you're talking about a fully qualified variable: 

      *{"$caller\::methodname"} = ...

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      'BigDB\::$cmd' is single-quoted, so creates a method named $cmd in package BigDB\ instead of a method named method1 in package BigDB. Try double quotes (where the backslash becomes harmless though unnecessary).
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