Re: Restoring the magic to the _ filehandle in Perl 5.8.9

[Animator]

The statement: 'The code below, in Perl 5.8.8 and 5.10.9 prints 1\n three times' is incorrect and confusing... I'm guessing you are confusing the different versions of perl...

Running 'the code below':

• Perl version: 5.006

  Use of uninitialized value in print at t.pl line 24.
  
  Undefined subroutine &main::_ called at t.pl line 28.
  

• Perl version: 5.008

  Use of -l on filehandle _ at t.pl line 24.
  Use of uninitialized value in print at t.pl line 24.
  
  Undefined subroutine &main::_ called at t.pl line 28.
  

• Perl version: 5.008008

  Use of -l on filehandle _ at t.pl line 24.
  Use of uninitialized value in print at t.pl line 24.
  
  Undefined subroutine &main::_ called at t.pl line 28.
  

• Perl version: 5.008009

  Use of -l on filehandle _ at t.pl line 24.
  Use of uninitialized value in print at t.pl line 24.
  
  Undefined subroutine &main::_ called at t.pl line 28.
  

• Perl version: 5.010000

  1
  1
  1
  

• Perl version: 5.011003

  1
  1
  1
  

[ikegami]

And the reason is that 5.10 doesn't consider "_" in "-X _" a function call.

>perl588\bin\perl -MO=Concise -e"sub _; -l _"
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
6     <1> ftlink vK/1 ->7
5        <1> entersub[t2] sKS/TARG,1 ->6
-           <1> ex-list sK ->5
3              <0> pushmark s ->4
-              <1> ex-rv2cv sK/128 ->-
4                 <#> gv[*_] s ->5
-e syntax OK

>perl589\bin\perl -MO=Concise -e"sub _; -l _"
7  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v ->3
6     <1> ftlink vK/1 ->7
5        <1> entersub[t2] sKS/TARG,1 ->6
-           <1> ex-list sK ->5
3              <0> pushmark s ->4
-              <1> ex-rv2cv sK/128 ->-
4                 <#> gv[*_] s ->5
-e syntax OK

>perl5100\bin\perl -MO=Concise -e"sub _; -l _"
4  <@> leave[1 ref] vKP/REFC ->(end)
1     <0> enter ->2
2     <;> nextstate(main 1 -e:1) v:{ ->3
3     <#> ftlink[*_] vR ->4
-e syntax OK