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).

       $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.

SEE ALSO
       Data::Dump



perl v5.14.2                                2013-05-10                  Data::Dump::Filtered(3pm)