in reply to Populate CGI from HTTP::Request wo/ using %ENV ?

To the best of my knowledge neither CGI nor CGI::Simple give you a way to populate header information directly into their respective objects; they just pull it from ENV automatically. Those are the only two CGI-related modules I've personally worked with; there may be others. A quick experiment shows you can localize %ENV though: 
#!perl -l
sub foo {
  local %ENV;
  $ENV{foo} = '1';
  print $ENV{foo};
}
foo;
print 'yes' if $ENV{foo} eq '1';

[download]
doesn't print "yes"

Replies are listed 'Best First'.
Re^2: Populate CGI from HTTP::Request wo/ using %ENV ?
by ikegami (Patriarch) on Mar 09, 2008 at 22:33 UTC

    local %ENV doesn't remove the magic attached to %ENV, so changes to %ENV still affect every thread, so the race condition remains. 

    THREAD 1                                THREAD 2
----------------------------------      ------------------------------
+----
{                                   T
local %ENV;                         i
-> Process's R_M remains undef      m
$ENV{REQUEST_METHOD} = 'GET';       e
-> Process's R_M becomes GET        |
                                    |   {
                                    |   local %ENV;
                                    v   -> Process's R_M becomes undef
                                        $ENV{REQUEST_METHOD} = 'PUT';
                                        -> Process's R_M becomes PUT

print($ENV{REQUEST_METHOD});
-> Prints process's R_M (PUT)
}
-> Process's R_M restored to undef

                                        print($ENV{REQUEST_METHOD});
                                        -> Prints process's R_M (undef
+)
                                        }
                                        -> Process's R_M restored to u
+ndef

    [download]

    That's why I suggested local *ENV instead. Then modifying %ENV doesn't change the processes environment.

    Update: Added illustration of two race conditions.

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom