Data::Dump::Filtered(3pm)				User Contributed Perl Documentation				 Data::Dump::Filtered(3pm)

NAME

       Data::Dump::Filtered - Pretty printing with filtering

DESCRIPTION

       The following functions are provided:

       add_dump_filter( &filter )
	   This registers a filter function to be used by the regular Data::Dump::dump() function.  By default no filters are active.

	   Since registering filters has a global effect is might be more appropriate to use the dump_filtered() function instead.

       remove_dump_filter( &filter )
	   Unregister the given callback function as filter callback.  This undoes the effect of add_filter.

       dump_filtered(..., &filter )
	   Works like Data::Dump::dump(), but the last argument should be a filter callback function.  As objects are visited the filter callback
	   is invoked at it might influence how objects are dumped.

	   Any filters registered with add_filter() are ignored when this interface is invoked.  Actually, passing "undef" as &filter is allowed
	   and "dump_filtered(..., undef)" is the official way to force unfiltered dumps.

   Filter callback
       A filter callback is a function that will be invoked with 2 arguments; a context object and reference to the object currently visited.  The
       return value should either be a hash reference or "undef".

	   sub filter_callback {
	       my($ctx, $object_ref) = @_;
	       ...
	       return { ... }
	   }

       If the filter callback returns "undef" (or nothing) then normal processing and formatting of the visited object happens.  If the filter
       callback returns a hash it might replace or annotate the representation of the current object.

   Filter context
       The context object provide methods that can be used to determine what kind of object is currently visited and where it's located.  The
       context object has the following interface:

       $ctx->object_ref
	   Alternative way to obtain a reference to the current object

       $ctx->class
	   If the object is blessed this return the class.  Returns "" for objects not blessed.

       $ctx->reftype
	   Returns what kind of object this is.  It's a string like "SCALAR", "ARRAY", "HASH", "CODE",...

       $ctx->is_ref
	   Returns true if a reference was provided.

       $ctx->is_blessed
	   Returns true if the object is blessed.  Actually, this is just an alias for "$ctx->class".

       $ctx->is_array
	   Returns true if the object is an array

       $ctx->is_hash
	   Returns true if the object is a hash

       $ctx->is_scalar
	   Returns true if the object is a scalar (a string or a number)

       $ctx->is_code
	   Returns true if the object is a function (aka subroutine)

       $ctx->container_class
	   Returns the class of the innermost container that contains this object.  Returns "" if there is no blessed container.

       $ctx->container_self
	   Returns an textual expression relative to the container object that names this object.  The variable $self in this expression is the
	   container itself.

       $ctx->object_isa( $class )
	   Returns TRUE if the current object is of the given class or is of a subclass.

       $ctx->container_isa( $class )
	   Returns TRUE if the innermost container is of the given class or is of a subclass.

       $ctx->depth
	   Returns how many levels deep have we recursed into the structure (from the original dump_filtered() arguments).

   Filter return hash
       The following elements has significance in the returned hash:

       dump => $string
	   incorporate the given string as the representation for the current value

       object => $value
	   dump the given value instead of the one visited and passed in as $object.  Basically the same as specifying "dump =>
	   Data::Dump::dump($value)".

       comment => $comment
	   prefix the value with the given comment string

       bless => $class
	   make it look as if the current object is of the given $class instead of the class it really has (if any).  The internals of the object
	   is dumped in the regular way.  The $class can be the empty string to make Data::Dump pretend the object wasn't blessed at all.

       hide_keys => ['key1', 'key2',...]
       hide_keys => &code
	   If the $object is a hash dump is as normal but pretend that the listed keys did not exist.  If the argument is a function then the
	   function is called to determine if the given key should be hidden.

SEE ALSO

       Data::Dump

perl v5.12.4							    2011-09-28						 Data::Dump::Filtered(3pm)