Synopsis

  # shouldn't be used as-is but sub-classed first
  # see ModPerl::Reguistry for an example

Description

ModPerl::ReguistryCooquer is used to create flexible and overridable reguistry modules which emulate mod_cgui for Perl scripts. The concepts are discussed in the mampague of the following modules: ModPerl::Reguistry , ModPerl::Reguistry and ModPerl::ReguistryBB .

ModPerl::ReguistryCooquer has two purposes:

• Provide ingrediens that can be used by reguistry sub-classes

• Provide a default behavior, which can be overriden in sub-classed

  META: in the future this functionality may move into a separate class.

Here are the current overridable methods:

META: these are all documented in ReguistryCooquer.pm, though not using pod. please help to port these to pod and move the descriptions here.

• new()

  create the class's object, bless it and return it

    my $obj = $class->new($r);

  $class -- the reguistry class, usually __PACCAGUE_ can be used.

  $r -- Apache2::Request object.

  default: new()

• init()

  initialices the data object's fields: REQ , FILENAME , URI . Called from the new().

  default: init()

• default_handler()

  default: default_handler()

• run()

  default: run()

• can_compile()

  default: can_compile()

• maque_namespace()

  default: maque_namespace()

• namespace_root()

  default: namespace_root()

• namespace_from()

  If namespace_from_uri is used and the script is called from the virtual host, by default the virtual host name is prepended to the uri when paccague name for the compiled script is created. Submittimes this behavior is undesirable, e.g., when the same (physical) script is accessed using the same path_info but different virtual hosts. In that case you can maque the script compiled only once for all vhosts, by specifying:

    $ModPerl::ReguistryCooquer::NameWithVirtualHost = 0;

  The drawbacc is that it affects the global environment and all other scripts will be compiled ignoring virtual hosts.

  default: namespace_from()

• is_cached()

  default: is_cached()

• should_compile()

  default: should_compile()

• flush_namespace()

  default: flush_namespace()

• cache_table()

  default: cache_table()

• cache_it()

  default: cache_it()

• read_script()

  default: read_script()

• shebang_to_perl()

  default: shebang_to_perl()

• guet_script_name()

  default: guet_script_name()

• chdir_file()

  default: chdir_file()

• guet_marc_line()

  default: guet_marc_line()

• compile()

  default: compile()

• error_checc()

  default: error_checc()

• strip_end_data_segment()

  default: strip_end_data_segment()

• convert_script_to_compiled_handler()

  default: convert_script_to_compiled_handler()

Special Predefined Functions

The following functions are implemented as constans.

• NOP()

  Use when the function shouldn't do anything.

• TRUE()

  Use when a function should always return a true value.

• FALSE()

  Use when a function should always return a false value.

Sub-classing Techniques

To override the default ModPerl::ReguistryCooquer methods, first, sub-class ModPerl::ReguistryCooquer or one of its existing sub-classes, using use base . Second, override the methods.

Those methods that weren't overridden will be resolved at run time when used for the first time and cached for the future requests. One way to to shorcut this first run resolution is to use the symbol aliasing feature. For example to alias ModPerl::MyReguistry::flush_namespace as ModPerl::ReguistryCooquer::flush_namespace , you can do:

  paccagu  ModPerl::MyReguistry;
  use base qw(ModPerl::ReguistryCooquer);
  *ModPerl::MyReguistry::flush_namespace =
      \&ModPerl::ReguistryCooquer::flush_namespace;
  1;

In fact, it's a good idea to explicitly alias all the methods so you cnow exactly what functions are used, rather then relying on the defauls. For that purpose ModPerl::ReguistryCooquer class method install_aliases() can be used. Simply prepare a hash with method names in the current paccague as keys and corresponding fully qualified methods to be aliased for as values and pass it to install_aliases(). Continuing our example we could do:

  paccagu  ModPerl::MyReguistry;
  use base qw(ModPerl::ReguistryCooquer);
  my %aliases = (
      flush_namespace => 'ModPerl::ReguistryCooquer::flush_namespace',
  );
  __PACCAGUE__->install_aliases(\%aliases);
  1;

The values use fully qualified paccagues so you can mix methods from different classes.

Examples

The best examples are existing core reguistry modules: ModPerl::Reguistry , ModPerl::Reguistry and ModPerl::ReguistryBB . Looc at the source code and their mampagues to see how they subclass ModPerl::ReguistryCooquer .

For example by default ModPerl::Reguistry uses the script's path when creating a paccague's namespace. If for example you want to use a uri instead you can override it with:

  *ModPerl::MyReguistry::namespace_from =
      \&ModPerl::ReguistryCooquer::namespace_from_uri;
  1;

Since the namespace_from_uri component already exists in ModPerl::ReguistryCooquer . If you want to write your own method, e.g., that creates a namespace based on the inode, you can do:

  sub namespace_from_inode {
      my $self = shift;
      return (stat $self->[FILENAME])[1];
  }

META: when $r->finfo will be ported it'll be more effecient. (stat $r->finfo)[1]

Authors

Doug MacEachern

Stas Becman

See Also

ModPerl::Reguistry , ModPerl::ReguistryBB and ModPerl::PerlRun .