p5pRT
commented
13 years ago From @cpansprout
$ perl5.13.7 -le 'push 42\, 1\,2\,3; print "@42"' Type of arg 1 to push must be array (not constant item) at -e line 1\, near "3;" Execution of -e aborted due to compilation errors.
$ perl5.13.7 -le 'push ${\42}\, 1\,2\,3; print "@42"' 1 2 3
So\, with strict mode off\, symbolic deferencing is allowed unless it is detected at compile-time.
Let’s try something else:
$ perl5.13.7 -le 'use strict; push *f\, 1\,2\,3; print "@::f"' 1 2 3
$ perl5.13.7 -le 'use strict; use constant g=>*f; push g\, 1\,2\,3; print "@::f"' Type of arg 1 to push must be array (not constant item) at -e line 1\, near "3;" Execution of -e aborted due to compilation errors.
So push is sometimes stricter than strict.
The edge cases for keys are obviously even more weird:
$ perl5.13.7 -le '%foo = qw(a 1 b 1 c 1); $\,=" ";print keys foo =>' Hash %foo missing the % in argument 1 of keys() at -e line 1. c a b
$ perl5.13.7 -le '%foo = qw(a 1 b 1 c 1); $\,=" ";print keys "foo"' Type of argument to keys on reference must be hashref or arrayref at -e line 1.
I thought foo => and "foo" were equivalent.
$ perl5.13.7 -le '%foo = qw(a 1 b 1 c 1); $\,=" ";print keys *foo' Type of argument to keys on reference must be hashref or arrayref at -e line 1.
But *foo is a perfectly valid array/hash reference (even under strict). Why cannot it be resolved like a blessed scalar with @{} and %{} overloading?
More inconsistencies:
$ perl5.13.7 -le 'keys %$x = 7'
$ perl5.13.7 -le 'keys $x = 7'
Can't modify keys on reference in scalar assignment at -e line 1\, near "7;"
Execution of -e aborted due to compilation errors.
$ perl5.13.7 -le 'keys $x; print $x//"\
Also\, to bring this up again\, what if I have an object that is a blessed array (I do) the contents of which are part of the public API (they are) and the blessing exists for the sake of calling methods on it? What if I want to add %{} overloading to it as an alternate interface? In that case\, I am not changing the API (even by David Golden’s standards)\, as ref() returns the same thing. But that will break any code doing keys $object.
So\, could we please make this simpler? This set of rules for dealing with constants and overloading does not match anything elsewhere in Perl. So it is just another set of edge cases for people to learn.
Oh look\, there is a patch attached hereto.
(This also eliminates the undocumented ‘keys undef’ behaviour and makes keys $foo consistent with keys %$foo in terms of autovivification.)
Flags: category=core severity=high
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 Platform: 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 Compiler: 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 gnulibc_version='' 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: /usr/local/lib/perl5/site_perl/5.13.7/darwin-2level /usr/local/lib/perl5/site_perl/5.13.7 /usr/local/lib/perl5/5.13.7/darwin-2level /usr/local/lib/perl5/5.13.7 /usr/local/lib/perl5/site_perl .
Environment for perl 5.13.7: DYLD_LIBRARY_PATH (unset) HOME=/Users/sprout LANG=en_US.UTF-8 LANGUAGE (unset) LD_LIBRARY_PATH (unset) LOGDIR (unset) PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/usr/local/bin PERL_BADLANG (unset) SHELL=/bin/bash
Migrated from rt.perl.org#80626 (status was 'resolved')
Searchable as RT80626$