Example 19.9: chemiserie

#!/usr/bin/perl -w # chemiserie - simple CGI shopping for shirts and sweaters  use strict; use CGI qw(:standard); use CGI::Carp qw(fatalsToBrowser);  my %States;             # state table mapping pages to functions my $Current_Screen;     # the current screen  # Hash of pages and functions.  %States = (     'Default'     => \&front_page,     'Shirt'       => \&shirt,     'Sweater'     => \&sweater,     'Checkout'    => \&checkout,     'Card'        => \&credit_card,     'Order'       => \&order,     'Cancel'      => \&front_page, );  $Current_Screen = param(".State") || "Default"; die "No screen for $Current_Screen" unless $States{$Current_Screen};  # Generate the current page.  standard_header();  while (my($screen_name, $function) = each %States) {     $function->($screen_name eq $Current_Screen); } standard_footer(); exit;   ################################ # header, footer, menu functions ################################  sub standard_header {     print header(), start_html(-Title => "Shirts", -BGCOLOR=>"White");     print start_form(); # start_multipart_form() if file upload }  sub standard_footer { print end_form(), end_html() }  sub shop_menu {     print p(defaults("Empty My Shopping Cart"),         to_page("Shirt"),         to_page("Sweater"),         to_page("Checkout")); }  ############################# # subroutines for each screen #############################  # The default page. sub front_page {     my $active = shift;     return unless $active;      print "<H1>Hi!</H1>\n";     print "Welcome to our Shirt Shop!  Please make your selection from ";     print "the menu below.\n";      shop_menu(); }  # Page to order a shirt from. sub shirt {     my $active = shift;     my @sizes  = qw(XL L M S);     my @colors = qw(Black White);      my ($size, $color, $count) =       (param("shirt_size"), param("shirt_color"), param("shirt_count"));      # sanity check     if ($count) {         $color = $colors[0] unless grep { $_ eq $color } @colors;         $size  = $sizes[0]  unless grep { $_ eq $size  } @sizes;         param("shirt_color", $color);         param("shirt_size",  $size);     }      unless ($active) {         print hidden("shirt_size")  if $size;         print hidden("shirt_color") if $color;         print hidden("shirt_count") if $count;         return;     }      print h1("T-Shirt");     print p("What a shirt!  This baby is decked out with all the options.",         "It comes with full luxury interior, cotton trim, and a collar",         "to make your eyes water!  Unit price: \$33.00");      print h2("Options");     print p("How Many?", textfield("shirt_count"));     print p("Size?",  popup_menu("shirt_size",  \@sizes ),         "Color?", popup_menu("shirt_color", \@colors));      shop_menu(); }  # Page to order a sweater from. sub sweater {     my $active = shift;     my @sizes  = qw(XL L M);     my @colors = qw(Chartreuse Puce Lavender);      my ($size, $color, $count) =       (param("sweater_size"), param("sweater_color"), param("sweater_count"));      # sanity check     if ($count) {         $color = $colors[0] unless grep { $_ eq $color } @colors;         $size  = $sizes[0]  unless grep { $_ eq $size  } @sizes;         param("sweater_color", $color);         param("sweater_size",  $size);     }      unless ($active) {         print hidden("sweater_size")  if $size;         print hidden("sweater_color") if $color;         print hidden("sweater_count") if $count;         return;     }      print h1("Sweater");     print p("Nothing implies preppy elegance more than this fine",         "sweater.  Made by peasant workers from black market silk,",         "it slides onto your lean form and cries out ``Take me,",         "for I am a god!''.  Unit price: \$49.99.");      print h2("Options");     print p("How Many?", textfield("sweater_count"));     print p("Size?",  popup_menu("sweater_size",  \@sizes));     print p("Color?", popup_menu("sweater_color", \@colors));      shop_menu(); }  # Page to display current order for confirmation. sub checkout {     my $active = shift;      return unless $active;      print h1("Order Confirmation");     print p("You ordered the following:");     print order_text();     print p("Is this right?  Select 'Card' to pay for the items",         "or 'Shirt' or 'Sweater' to continue shopping.");     print p(to_page("Card"),         to_page("Shirt"),          to_page("Sweater")); }  # Page to gather credit-card information. sub credit_card {     my $active = shift;     my @widgets = qw(Name Address1 Address2 City Zip State Phone Card Expiry);      unless ($active) {         print map { hidden($_) } @widgets;         return;     }      print pre(p("Name:          ", textfield("Name")),       p("Address:       ", textfield("Address1")),       p("               ", textfield("Address2")),       p("City:          ", textfield("City")),       p("Zip:           ", textfield("Zip")),       p("State:         ", textfield("State")),       p("Phone:         ", textfield("Phone")),       p("Credit Card #: ", textfield("Card")),       p("Expiry:        ", textfield("Expiry")));      print p("Click on 'Order' to order the items.  Click on 'Cancel' to return shopping.");      print p(to_page("Order"), to_page("Cancel")); }  # Page to complete an order. sub order {     my $active = shift;      unless ($active) {         return;     }      # you'd check credit card values here      print h1("Ordered!");     print p("You have ordered the following toppings:");     print order_text();      print p(defaults("Begin Again")); }  # Returns HTML for the current order ("You have ordered ...") sub order_text {     my $html = '';      if (param("shirt_count")) {         $html .= p("You have ordered ", param("shirt_count"),            " shirts of size ",  param("shirt_size"),            " and color ", param("shirt_color"), ".");     }     if (param("sweater_count")) {         $html .= p("You have ordered ",  param("sweater_count"),            " sweaters of size ", param("sweater_size"),            " and color ", param("sweater_color"), ".");     }     $html = p("Nothing!") unless $html;     $html .= p("For a total cost of ", calculate_price());     return $html; }   sub calculate_price {     my $shirts   = param("shirt_count")   || 0;     my $sweaters = param("sweater_count") || 0;     return sprintf("\$%.2f", $shirts*33 + $sweaters * 49.99); } 



 sub to_page { submit(-NAME => ".State", -VALUE => shift) }