http://www.perlmonks.org?node_id=820051


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

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