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[perl #80628] [PATCH] __SUB__

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Father Chrysostomos
December 12, 2010 12:26
[perl #80628] [PATCH] __SUB__
Message ID:
# New Ticket Created by  Father Chrysostomos 
# Please include the string:  [perl #80628]
# in the subject line of all future correspondence about this issue. 
# <URL: >

This patch adds a __SUB__ keyword that returns the current subroutine, or undef for the main program, a special block, or an eval.

If there are no objections, I will add docs and push this shortly before 5.13.8.

I first thought of adding this to make recursive lexicals subs easier to write (whenever they are added):

my sub foo { __SUB__->() }

my sub foo;  # the alternative
my sub foo { foo() }

The really neat thing, which I realised only after writing it, is that it allows for recursive closures to be written much more simply:

sub make_recursive_function {
  my $arg = shift;
  sub {
    print "$_[0]\n";
    __SUB__->($_[0] + 1) if $_[0] < $arg;

as opposed to:

use Scalar::Util;
sub make_recursive_function {
  my $arg = shift;
  my $sub;
  my $life_raft = $sub = sub {
    print "$_[0]\n";
    &$sub($_[0] + 1) if $_[0] < $arg;

[Reminder to myself: I need to add it to as well.]

Site configuration information for perl 5.13.7:

Configured by sprout at Thu Dec  9 14:53:58 PST 2010.

Summary of my perl5 (revision 5 version 13 subversion 7) configuration:
  Snapshot of: 9e9fdd5de1676d607ddf9b9f10b8df2659af3ded
    osname=darwin, osvers=10.4.0, archname=darwin-2level
    uname='darwin pint.local 10.4.0 darwin kernel version 10.4.0: fri apr 23 18:28:53 pdt 2010; root:xnu-1504.7.4~1release_i386 i386 '
    config_args='-de -Dusedevel -DDEBUGGING'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=undef, use64bitall=undef, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
    cc='cc', ccflags ='-fno-common -DPERL_DARWIN -no-cpp-precomp -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include',
    optimize='-O3 -g',
    cppflags='-no-cpp-precomp -fno-common -DPERL_DARWIN -no-cpp-precomp -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.2.1 (Apple Inc. build 5664)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib
    libs=-ldbm -ldl -lm -lutil -lc
    perllibs=-ldl -lm -lutil -lc
    libc=/usr/lib/libc.dylib, so=dylib, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/usr/local/lib -fstack-protector'

Locally applied patches:

@INC for perl 5.13.7:

Environment for perl 5.13.7:
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

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