It's indeed possible to bend the parser in a way that it thinks BEGIN and family are subs

use strict;
use warnings;
use Keyword::Simple;

sub no_begin ($&){
    warn "no_begin(@_) called";
}

my @code;

BEGIN{
    my @compile_blocks = qw(BEGIN UNITCHECK CHECK INIT END);

    for my $block (@compile_blocks) {

        # bend parser
        Keyword::Simple::define $block, sub {
            my ($ref) = @_;
            substr($$ref, 0, 0) = "no_begin '$block', sub";
        };

        # test code
        push @code , <<__CODE__;
        $block { die "owened by $block" }
__CODE__

    }
}

BEGIN { die "owened by BEGIN" };
UNITCHECK { die "owened by UNITCHECK" };
CHECK { die "owened by CHECK" };
INIT { die "owened by INIT" };
END { die "owened by END" };

eval join "\n", @code;
[download]

-*- mode: compilation; default-directory: "d:/tmp/pm/" -*-
Compilation started at Wed Oct  6 19:04:01

C:/Strawberry/perl/bin\perl.exe -w d:/tmp/pm/KW_simple_regex_BEGIN.pl 
no_begin(BEGIN CODE(0x694268)) called at d:/tmp/pm/KW_simple_regex_BEG
+IN.pl line 6.
no_begin(UNITCHECK CODE(0x6556d0)) called at d:/tmp/pm/KW_simple_regex
+_BEGIN.pl line 6.
no_begin(CHECK CODE(0x6942b0)) called at d:/tmp/pm/KW_simple_regex_BEG
+IN.pl line 6.
no_begin(INIT CODE(0x6c8aa0)) called at d:/tmp/pm/KW_simple_regex_BEGI
+N.pl line 6.
no_begin(END CODE(0x6c8c38)) called at d:/tmp/pm/KW_simple_regex_BEGIN
+.pl line 6.
Bareword found where operator expected at (eval 5) line 5, near "}

        CHECK"
    (Missing operator before CHECK?)
[download]

But unfortunately does evaling the code not catch parsing errors anymore... (reason here BEGIN{} blocks don't need a trailing semicolon)

so the answer is:

• Yes BEGIN* blocks can be disabled.
• But this is best done in an extra process

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.