Re: Inheritable pragma ... or how I learnt perls' compilation order

I'm not sure I follow what you're trying to do, but my reading reminds me of BEGIN, UNITCHECK, CHECK, INIT, and END blocks, which I also don't fully understand.

If you want to ensure that there are no other constructors before you, I don't think you'll have much luck. Any code any where can bless into your class and cross its digits in hopes that nothing goes wrong.

I could imagine perhaps a new() method that notes its results (with weak references, of course) in a lexical hash. Then other methods in the class can check up on the objects they're called on in this table of "allowed" objects and throw a tantrum if a transgression is detected. There would be a performance penalty, of course. Also, you can't stop someone from "subclassing" via delegation. Such an object could even override UNIVERSAL::isa so as to pretend to be your object.

So what are you really trying to gain here? What is the rationale behind these requirements? What do you want to protect yourself against?

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Re^2: Inheritable pragma ... or how I learnt perls' compilation order by Bloodnok (Vicar) on Aug 06, 2008 at 10:01 UTC
Hi , Thanx for your insight - looks like `UNITCHECK` or, probably, `CHECK` would be the way to go. Way to go kyle :-)) Update Thinking about it, using the `CHECK` block would be best as it's also run when using `perl -c ...`. Something like the following would possibly suffice (based on code supplied elsewhere in the thread 702588)... `CHECK { my $dp = B::Deparse->new(); while (my ($pkg, $hash) = each %INTERFACES) { while (my ($var, $glob) = each %{"${pkg}::"}) { next unless defined &$glob; croak "Constructor detected: ${pkg}::$var" if $dp->coderef2text(\&{"${pkg}::$var"}) =~ /\bbless\b/; } } }` [download] Note that this is not too much more than thinking aloud i.e. code untried and untested ... yet;-) Further Update Corrected typo (missing trailing slash) in RE At last, a user level that overstates my experience :-))	[reply] [d/l] [select]

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Re^2: Inheritable pragma ... or how I learnt perls' compilation order
by Bloodnok (Vicar) on Aug 06, 2008 at 10:01 UTC

Thanx for your insight - looks like UNITCHECK or, probably, CHECK would be the way to go.

Way to go kyle :-))

Update

Thinking about it, using the CHECK block would be best as it's also run when using perl -c .... Something like the following would possibly suffice (based on code supplied elsewhere in the thread 702588)...

CHECK {
  my $dp = B::Deparse->new();
  while (my ($pkg, $hash) = each %INTERFACES) {
    while (my ($var, $glob) = each %{"${pkg}::"}) {
      next unless defined &$glob;
      croak "Constructor detected: ${pkg}::$var" if
        $dp->coderef2text(\&{"${pkg}::$var"}) =~ /\bbless\b/;
    }
  }
}
[download]

Further Update

Corrected typo (missing trailing slash) in RE

At last, a user level that overstates my experience :-))

[reply]
[d/l]
[select]