NAME
DS::Transformer - receives, transforms and passes on rows
DESCRIPTION
This class is the base class of all transformers in DS. If you need to write a transformer, first consider if DS::Transformer::Sub will do. It supports any kind of row-wise transformations where there is a one-to-one correspondence between incoming and outgoing rows.
SUPER CLASSES
DS::Transformer is a mixin of DS::Source and DS::Target.
METHODS
process( $row )
Method for processing of ingoing data. This method is supposed to be overridden. By default it will return $row.
new( $class, $in_type, $out_type, $source, $target )
Constructor. Instantiates an object of class $class, taking the type $in_type, returning the type $out_type, attached to the source $source and attaced to the target $target. Besides $class, any of the parameters can be left out.
attach_target( $target )
Attaches target $target to this object. This method also triggers type checking, ensuring that the outgoing type of this object is sufficient for $target. If the type check fails, an exception is thrown.
target( $target )
This is a method mostly for internal use. It will get or set the target, bypassing type checks.
pass_row( $row )
Calling this metod will cause the transformer to pass $row to the target $target.
out_type( $type )
This is an accessor that gets or sets the outgoing type of this object.
receive_row( $row )
Triggers processing of $row. This method calls process with $row, and then passes the result to pass_row.
attach_source( $source )
Attaches $source as source. This method also validates data types by calling validate_source_type, throwing an exception if the validation fails.
source( $source )
Accessor for source. This method sets the source of this object and triggers type checking.
validate_source_type( $source_type )
Validates source type. If the $source_type is not valid, it returns false, true otherwise. By default, this method ensures that the ingoing type of this object contains no fields not specified in $source_type. Override if you need more complex checking.
in_type( $type )
Accessor for ingoing type.
SEE ALSO
DS::Transformer::Sub, DS::Source, DS::Target.
AUTHOR
Written by Michael Zedeler.