This sounds like a job for anonymous subs:

    my %constructor= {
        MSWin32 => sub { FTP::Session::Win32->new( @_ ) },
        HPUX => sub { FTP::Session::HPUX->new( @_ ) },
    }
    my $ctor= $constructor{$^O};
    die "No constructor for $^O"   if  ! $ctor;
    my $session= $ctor->( ... );
    # Old Perl requires:  $session= &$ctor( ... );

[download]

The next best thing is UNIVERSAL::can(), which returns a reference to a named method. But then you need to cache each class name so that you can pass that in to the sub that you got a reference to: 

    my %class= {
        MSWin32 => "FTP::Session::Win32",
        HPUX => "FTP::Session::HPUX",
    }
    my %constructor= {
        MSWin32 => FTP::Session::Win32->can("new"),
        HPUX => FTP::Session::HPUX->can( "new" ),
    }
    my $ctor= $constructor{$^O};
    die "No constructor for $^O"   if  ! $ctor;
    my $session= $ctor->( $class{$^O}, ... );
    # Old Perl requires:  $session= &$ctor( $class{$^O}, ... );

[download]

In reply to Re: Calling a class constructor as a function on input arguments by tye
in thread Calling a class constructor as a function on input arguments by princepawn

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.