How to resolve 'constant flags' for Windows and Linux clients in Perl?

I am using following Linux and Windows perl libraries as given below -

Linux:

use Fcntl; 
use File::FcntlLock

Windows:

use Win32::API;
use Win32API::File qw(:Func :Misc :FILE_:FILE_FLAG_ :FILE_SHARE_ :FILE_ATTRIBUTE_ :GENERIC_ )

So on the basis of the host(Linux or Windows) I am using to run the scripts, I am loading the package-

my $linux_packages = "use Fcntl; use File::FcntlLock; use File::Copy;1;";
my $window_packages
    = "use Win32::API; use Win32API::File qw(:Func :Misc :FILE_ "
    . ":FILE_FLAG_ :FILE_SHARE_ :FILE_ATTRIBUTE_ :GENERIC_ );1;";

if ( $Hosttype =~ /unix/ ) {

    eval "$linux_开发者_运维知识库packages";


} elsif ( $Hosttype =~ /windows/ ) {

    eval "$window_packages";

} 

Now i am trying to use the flags from Linux or windows client , but if i run the script on Linux client it thrown the error for windows flags as

SCRIPT ERROR: Bareword "GENERIC_READ" not allowed while "strict subs" in use

And if quoted GENERIC_READ, it is used as string not as actual flag and via versa.

How to resolve?

You should factor out operating system specific bits of your own code into separate modules that present a unified interface, and then require the appropriate module depending on operating system.

To do that, you can use Sys::Info::OS and require and import. Something along the lines of the following (untested) should work:

use strict; use warnings;

use Sys::Info::OS;

BEGIN {
    my $os = Sys::Info::OS->new;
    if ($os->is_windows) {
        require Win32::API;
        Win32::API->import;

        require Win32API::File;
        Win32API::File->import(qw(
            :Func
            :Misc
            :FILE_
            :FILE_FLAG_
            :FILE_SHARE_
            :FILE_ATTRIBUTE_
            :GENERIC_
        ));
    }
    elsif ($os->is_linux) {
        require Fcntl;
        Fcntl->import;

        require File::FcntlLock;
        File::FcntlLock->import;

        require File::Copy;
        File::Copy->import;
    }
    else {
        die sprintf "Unknown OS: %s\n", $os->name;
    }
}

# rest of the code