Re: RFC 106 (v1) Yet another lexical variable proposal: lexical variables made default

"J. David Blackstone" <[email protected]> writes:

[...]

>   I agree with you.  However, I am unable to find a case in which a
> package global could not be replaced with a lexical defined in the
> module's .pm file and an accessor method for it.  Even if you are
> extending a class, you can still provide this.

Modes.  Emacs Lisp uses this (I'm not convinced that's a
recommendation).  Suppose I have a flag $PKG::verbose which prints
descriptive messages to LOG if 1 (but if 2 does something else, since
bits are significant).  If it's a global, I can do this:

    {
      local $PKG::verbose = 1;
      PKG::frobnicate;
    }
    # Back to previous verbosity level

Lacking true dynamic variables, this doesn't work (although
unwind-protect, if we had that, could also provide for restoring
variables).

The best we can do is:

    {
      my $old_verbosity = PKG::get_verbose;
      PKG::set_verbose(1);
      PKG::frobnicate;
      PKG::set_verbose($old_verbosity);
    }

but that doesn't work in the presence of eval{}/die.  So you also need 
unwind-protect.

[...]

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Ariel Scolnicov        |"GCAAGAATTGAACTGTAG"            | [email protected]
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