http://www.perlmonks.org?node_id=864278


in reply to Re^5: Writing a better Modern::Perl
in thread Writing a better Modern::Perl

Of course you won't necessarily get an error. If you would necessarily get an error, there would be no need to add features in the first place. Your expectations don't make only sense. features affects how code behaves. If you stop using it, it will behave differently. 

$ perl -e'           sub say(&@) { "..." } say { "..." };'

$ perl -e'use 5.010; sub say(&@) { "..." } say { "..." };'
syntax error at -e line 1, near "};"
Execution of -e aborted due to compilation errors.

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$ perl -e'           print $x;'

$ perl -e'use 5.012; print $x;'
Global symbol "$x" requires explicit package name at -e line 1.
Execution of -e aborted due to compilation errors.

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$ perl -e'           die "Validation error" if uc(chr(0xE9))=~/\xC9/;'

$ perl -e'use 5.012; die "Validation error" if uc(chr(0xE9))=~/\xC9/;'
Validation error at -e line 1.

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In Section Meditations