wondering why does 5.10 features are not working

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I am just reading and testing the 5.10 features of perl. Tested "say", "state" but it works only when 'use v5.10' is there in file. Why it is ?

perl version available by default in my machine is

perl -v

This is perl, v5.10.1 (*) built for i486-linux-gnu-thread-multi

Copyright 1987-2009, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the GNU General Public License, which may be found in the Perl 5 
+source kit.

Complete documentation for Perl, including FAQ lists, should be found 
+on this system using "man perl" or "perldoc perl".  If you have acces
+s to the Internet, point your browser at http://www.perl.org/, the Pe
+rl Home Page.
[download]

without version requirement

perl -e 'say "test"';

String found where operator expected at -e line 1, near "say "test""
    (Do you need to predeclare say?)
syntax error at -e line 1, near "say "test""
Execution of -e aborted due to compilation errors.
[download]

with version requirement it works fine

perl -M5.10.1 -e 'say "test"';
test
[download]

Is it my misunderstanding, please explain me. Google search with these words 'say', 'state', are not giving useful results. Thanks for your help.

Comment on wondering why does 5.10 features are not working Select or Download Code

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Re: wondering why does 5.10 features are not working by moritz (Cardinal) on Sep 23, 2011 at 19:31 UTC
For backward compatibility, the features that involve a new keyword need to be enabled explicitly, either via `use 5.010;` or `use feature ':5.10';` or `use feature qw/say switch state/;` In onliners, using `-E` instead of `-e` also enables all new features: `perl -wE 'say 42'` [download] Perl 6 - second systems done right	[reply] [d/l] [select]
Re^2: wondering why does 5.10 features are not working by Anonymous Monk on Sep 23, 2011 at 20:37 UTC
This is why I like perl very much ! Instant & good responses ! Thank you very much !	[reply]
Re: wondering why does 5.10 features are not working by BrowserUk (Patriarch) on Sep 23, 2011 at 19:30 UTC
Use `-E` instead of `-e` to enable features on the command line: `c:\test>perl -E"say $]" 5.010001` [download] Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re: wondering why does 5.10 features are not working by ikegami (Patriarch) on Sep 23, 2011 at 19:39 UTC
`use feature qw( state );` is required to use `state`. This requirement prevents the following perfectly legitimate code from breaking when someone upgrades Perl: `$ perl -e'sub state { print "I state: @_\n" } state("foo");' I state: foo` [download] `use feature qw( state );` is available via `use feature ':5.10';`, which is available via `use 5.010;`. Same goes for `say`. The documentation for `say` and the documentation for `state` both mention this.	[reply] [d/l] [select]