Hi,
On 06.12.2016 00:49, CARAYOL Jean-Pierre wrote:
> Hi,
>
>
>
> I don't understand why the 2 following Perl6 programs give a different
> result when running.
>
> If someone could give me an explanation, it will help me a lot. Many thanks.
>
>
>
> /(Note the 2 programs run on Linux and the Linux environment variable
> $toto is set to "totoenv". ( export toto=totenv )/
>
>
> _Program1 :_
>
> /cattest051.pl6/_
> _
>
> #!/opt/rakudo-star-2016.10/bin/perl6
> use v6;
>
> grammar TEST {
> rule TOP { :i \s* <varenv> }
> token varenv {'$'<mot> }
> token mot { <[a..z A..Z 0..9 =\-_!~'():@&+$,\']>+ }
> }
>
> class ActionsTest {
> method TOP ($/) { $/.make( ~%*ENV{$<varenv><mot>}); }
> }
>
> my $actions = ActionsTest.new;
> my $script = "\$toto" ;
> my $scr = TEST.parse($script,:$actions);
> say $scr;
> say $scr.made;
> ===>./test051.pl6
> ｢$toto｣
> varenv => ｢$toto｣
> mot => ｢toto｣
> *totoenv*
> ----------------
> This programs runs fine and displayed the value for the toto environment
> variable.
>
>
>
> _Program2:_
>
> __cat test052.pl6
>
> grammar TEST {
> rule TOP { :i \s* <varenv> }
> token varenv {'$'<mot> }
> token mot { <[a..z A..Z 0..9 =\-_!~'():@&+$,\']>+ }
> }
>
> class ActionsTest {
> method varenv ($/) { $/.make( %*ENV{$<varenv><mot>}); }
> method TOP ($/) { $/.make( ~$/); }
$/.make stores the result in $/.made, so the second line should be
method TOP($/) { $/.make($<mot>.made) }
HTH,
Moritz
> }
>
> my $actions = ActionsTest.new;
> my $script = "\$toto" ;
> my $scr = TEST.parse($script,:$actions);
> say $scr;
> say $scr.made;
>
> ===>
> Use of Nil in string context
> in method varenv at ./test052.pl6 line 14
> ｢$toto｣
> varenv => ｢$toto｣
> mot => ｢toto｣
> $toto
> ----------------
> This program displays an error message and doesn't find the value of
> toto environment variable.
>
>
> The only difference between the 2 programs is instruction "make(
> %*ENV{$<varenv><mot>}" is part of the TOP method in the program 1 and
> part of the varenv method in program 2.
>
> I'm certainly missing something but I don't understand why program 2
> doesn't work. I'm very interested to get explanations for that. It will
> help me to understand how to modify and AST using Perl6.
>
>
> Thanks a lot for your help.
>
> Best regards,
>
> Jean-Pierre
>
>
--
Moritz Lenz
https://deploybook.com/ -- https://perlgeek.de/ -- https://perl6.org/
