man page Data::Dump::Filtered section 3

Data::Dump::Filtered(3)

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).

       $ctx->expr
       $ctx->expr( $top_level_name )
           Returns an textual expression that denotes the current object.  In
           the expression $var is used as the name of the top level object
           dumped.  This can be overridden by providing a different name as
           argument.

   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.

NAME

DESCRIPTION

SEE ALSO