Re^2: how to import::into v5.020

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Re^3: how to import::into v5.020
by ikegami (Patriarch) on Nov 16, 2023 at 00:21 UTC

Not quite.

use v5.20;
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is closer to

BEGIN { require v5.20; }
no feature qw( :all );      # `use v5.10;`+
use feature qw( :5.20 );    # `use v5.10;`+
use strict;                 # `use v5.12;`+
#use warnings;              # `use v5.35;`+
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So you want

require v5.20;
feature->unimport::out_of( $caller, ':all' );  # `use v5.10;`+
feature->import::into( $caller, ':5.20' );     # `use v5.10;`+
strict->import::into( $caller );               # `use v5.12;`+
#warnings->import::into( $caller );            # `use v5.35;`+
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Turning off all features first is especially important with 5.35+ because use v5.35; and higher turn off features which are enabled by default. Specifically,

use v5.35; and higher turns off the indirect and multidimensional normally-enabled features, and
use v5.37; and higher turns off the bareword_filehandles normally-enabled feature

$ perl -e'use v5.35; abc def;'
Bareword found where operator expected (Do you need to predeclare "abc
+"?) at -e line 1, near "abc def"
syntax error at -e line 1, near "abc def"
Execution of -e aborted due to compilation errors.

$ perl -e'use feature qw( :5.35 ); abc def;'
Can't locate object method "abc" via package "def" (perhaps you forgot
+ to load "def"?) at -e line 1.

$ perl -e'no feature qw( :all ); use feature qw( :5.35 ); abc def;'
Bareword found where operator expected (Do you need to predeclare "abc
+"?) at -e line 1, near "abc def"
syntax error at -e line 1, near "abc def"
Execution of -e aborted due to compilation errors.
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