p5pRT
commented
24 years ago From marcel.grunauer@lovely.net
I've come across a behavior of the qw() operator in conjunction with the x operator that I can't explain. I've checked perlop.
#!/usr/bin/perl -w use strict; my %test; @test{qw/a b c/} = ('n') x 3; print "$_ => $test{$_}\n" foreach keys %test;
produces\, as expected:
a => n b => n c => n
If I replace the hash slice line above with
@test{qw/a b c/} = qw/n/ x 3;
it produces:
Bareword "x" not allowed while "strict subs" in use at ... Unquoted string "x" may clash with future reserved word at ... syntax error at ...\, near "qw/n/ x " Number found where operator expected at ...\, near "x 3" (Do you need to predeclare x?)
The following two work ok:
@test{qw/a b c/} = (qw/n/) x 3; @test{qw/a b c/} = (split(' '\, q/n/)) x 3;
According to Tad McClellan (tadmc@metronet.com):
Note also that you get the same messages if you replace the line above with just:
x 3;
Looks like perl is taking "@test{qw/a b c/} = qw/n/" as an entire statement\, and then resuming the parse...
According to Abigail (abigail@delanet.com):
Based on [the repetition operator documentation]\, I would assume that
@​test\{qw/a b c/\} = qw/n/ x 3;would lead to:
%test = \(a => '111'\, b => undef\, c => undef\);This is because the left operand of x will be evaluated in scalar context\, hence the split qw// does is done to @_\, and the amount of produced fields is returned. This being 1\, leads to 1 x 3 which is '111'.
Site configuration information for perl 5.00502:
Summary of my perl5 (5.0 patchlevel 5 subversion 02) configuration: Platform: osname=MSWin32\, osvers=4.0\, archname=MSWin32-x86-object uname='' hint=recommended\, useposix=true\, d_sigaction=undef usethreads=undef useperlio=undef d_sfio=undef Compiler: cc='cl.exe'\, optimize='-O2 -MD -DNDEBUG -TP -GX'\, gccversion= cppflags='-DWIN32' ccflags ='-O2 -MD -DNDEBUG -TP -GX -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT -DPERL_OBJECT' stdchar='char'\, d_stdstdio=define\, usevfork=false intsize=4\, longsize=4\, ptrsize=4\, doublesize=8 d_longlong=undef\, longlongsize=8\, d_longdbl=define\, longdblsize=10 alignbytes=8\, usemymalloc=n\, prototype=define Linker and Libraries: ld='link'\, ldflags ='-nologo -nodefaultlib -release -machine:x86' libpth="C:\usr\lib\core" "C:\Program Files\Mts\Lib" libs= oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib version.lib odbc32.lib odbccp32.lib PerlCRT.lib libc=C:\usr\lib\core\PerlCRT.lib\, so=dll\, useshrplib=yes\, libperl=perlcore.lib Dynamic Linking: dlsrc=dl_win32.xs\, dlext=dll\, d_dlsymun=undef\, ccdlflags=' ' cccdlflags=' '\, lddlflags='-dll -nologo -nodefaultlib -release -machine:x86'
Locally applied patches: ACTIVEPERL_LOCAL_PATCHES_ENTRY
@INC for perl 5.00502: C:\root\perldev\lib C:\usr\lib C:\usr\site\lib .
Environment for perl 5.00502: HOME=C:\root LANG (unset) LD_LIBRARY_PATH (unset) LOGDIR (unset)
PATH=c:\cygnus\CYGWIN~1\H-I586~1\bin;.;C:\usr\bin;C:\WINNT\system32;C:\WINNT;C:\rootbin;c:\cygnus\CYGWIN~1\H-I586~1\bin;G:\jdk1.2.2\bin;c:\Program Files\Winzip;C:\DAYNA PERL5LIB=C:\root\perldev\lib PERL_BADLANG (unset) SHELL=/bin/sh
-- Marcel\, Perl Padawan sub AUTOLOAD{$_=$AUTOLOAD;s;.*::;;;y;_; ;;print}&Just_Another_Perl_Hacker;
Migrated from rt.perl.org#1687 (status was 'resolved')
Searchable as RT1687$