evalexpr?evaltrue:evalfalse would like evaltrue defaulted by evalexpr

[p5pRT]

Migrated from rt.perl.org#3559 (status was 'resolved')

Searchable as RT3559$

[p5pRT]

From mar@cf.nettuno.it

This is a bug report for perl from mar@​cf.nettuno.it,
generated with the help of perlbug 1.28 running under perl v5.6.0.

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This is not a bug, but an usefull and easy enhancement -i think​:
the syntax and use of
  evalexpr?evaltruecase​:evalfalsecase
can be enhanced with the capability of absence of evaltruecase expression

this absence can return by default the value of evalexpr

having
  evalexpr?​:evalfalsecase
similar but more efficient that (typical...)
  evalexpr?evalexpr​:evalfalsecase

actually perl returns syntax error near "?​:"

for efficency and code more light

All the best,
Marco Munari <mar@​chiara.dei.unipd.it>
--
/~v~~\ .​::​: ... Marco Munari ... :​::​::​::​::​::​::​::​::​:: Univers. :​::.
\_ */ :​:: mailto​:mar@​cf.nettuno.it?subject=.signature :​:
.\..\. :​: :​:
  \A ...​::​: :​:
  YV :​:: "Progress is implicitly due to perfect exceptions" :​::
  / \ :​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​::​:.
x(t),y(t) = th(3t-34.5)*e^[-(3t-34.5)^2]/2-4.3+e^(-1.8/t^2)/(.8*atg(t-
3)+2)(t-1.8)-.3th(5t-42.5),(1.4e^[-(3t-34.5)^2]+1-sgn[|t-8.5|-.5]*1.5*
|sin(pi*t)|^[2e^(-(t-11.5)^2)+.5+e^(-(.6t-3.3)^2)])/(.5+t)+1 ; 0<t<14

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Flags​:
  category=core
  severity=none

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Site configuration information for perl v5.6.0​:

Configured by pixel at Fri Mar 31 16​:32​:49 CEST 2000.

Summary of my perl5 (revision 5.0 version 6 subversion 0) configuration​:
  Platform​:
  osname=linux, osvers=2.2.15-0.16mdksmp, archname=i386-linux
  uname='linux kenobi.mandrakesoft.com 2.2.15-0.16mdksmp #1 smp mon mar 13 16​:40​:10 cet 2000 i686 unknown '
  config_args='-des -Dprefix=/usr -Darchname=i386-linux -Dd_dosuid -Dd_semctl_semun -Di_db -Di_ndbm -Di_gdbm -Ud_csh -Dman3dir=/usr/lib/perl5/man/man3 -Doptimize=-O3 -fomit-frame-pointer -fno-exceptions -fno-rtti -pipe -s -mpentium -mcpu=pentium -march=pentium -ffast-math -fexpensive-optimizations'
  hint=recommended, useposix=true, d_sigaction=define
  usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef
  useperlio=undef d_sfio=undef uselargefiles=define
  use64bitint=undef use64bitall=undef uselongdouble=undef usesocks=undef
  Compiler​:
  cc='cc', optimize='-O3 -fomit-frame-pointer -fno-exceptions -fno-rtti -pipe -s -mpentium -mcpu=pentium -march=pentium -ffast-math -fexpensive-optimizations', gccversion=2.95.3 19991030 (prerelease)
  cppflags='-fno-strict-aliasing'
  ccflags ='-fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64'
  stdchar='char', d_stdstdio=define, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
  ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
  alignbytes=4, usemymalloc=n, prototype=define
  Linker and Libraries​:
  ld='cc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib
  libs=-lnsl -ldl -lm -lc -lposix -lcrypt
  libc=/lib/libc-2.1.3.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
  cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Locally applied patches​:
 

---

@​INC for perl v5.6.0​:
  /usr/lib/perl5/5.6.0/i386-linux
  /usr/lib/perl5/5.6.0
  /usr/lib/perl5/site_perl/5.6.0/i386-linux
  /usr/lib/perl5/site_perl/5.6.0
  /usr/lib/perl5/site_perl/5.005/i386-linux
  /usr/lib/perl5/site_perl/5.005
  /usr/lib/perl5/site_perl
  .

---

Environment for perl v5.6.0​:
  HOME=/home/mar
  LANG=en
  LANGUAGE=en
  LC_ALL=en
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)
  PATH=/usr/local/bin​:/bin​:/usr/bin​:/opt/jdk-1.2.2/bin​:/usr/X11R6/bin​:/home/mar/bin​:/opt/jdk-1.2.2/bin​:/usr/X11R6/bin
  PERL_BADLANG (unset)
  SHELL=/bin/bash

[p5pRT]

From [Unknown Contact. See original ticket]

Marco Munari <mar@​cf.nettuno.it> wrote

having
evalexpr?​:evalfalsecase
similar but more efficient that (typical...)
evalexpr?evalexpr​:evalfalsecase

The || operator already does exactly what you are asking for.

Mike Guy

[p5pRT]

From [Unknown Contact. See original ticket]

On 20 Jul 2000, Marco Munari wrote​:

having
evalexpr?​:evalfalsecase
similar but more efficient that (typical...)
evalexpr?evalexpr​:evalfalsecase

perhaps you want the equivalent (and currently legal)​:

  $val = evalexpr || evalfalsecase;

-Aaron

[p5pRT]

From @ysth

In article <Pine.A41.4.05.10007210845000.67816-100000@​node13.unix.Virginia.EDU>,
Aaron J Mackey <ajm6q@​virginia.edu> wrote​:

On 20 Jul 2000, Marco Munari wrote​:

having
evalexpr?​:evalfalsecase
similar but more efficient that (typical...)
evalexpr?evalexpr​:evalfalsecase

perhaps you want the equivalent (and currently legal)​:

$val = evalexpr || evalfalsecase;

Subtle difference​: C<a ? a : b> gives boolean context to the first a.
The second a and the b get whatever context comes from the outside.
C<a || b> gives scalar context to the a, while b gets its context from
the outside.