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Elements in XML always have an order which is in contrast to hash keys
in Perl.

XML elements names on same level can be repeated, not so in hashes.

XML element names are more limited than arbitrary strange hash keys.

XML elements can have attributes and those can be addressed by XPath;
Perl data structures do not need this. On the other side, data
structures in Perl can contain blessed elements, DPath can address
this.

XML has namespaces, data structures have not.

Arrays starting with index 1 as in XPath would be confusing to read
for data structures.

DPath allows filter expressions that are in fact just Perl expressions
not an own sub language as in XPath.

=head2 Comparison with Data::Path

There is a similar approach on CPAN, L<Data::Path|Data::Path>. Here is
a comparison matrix between L<Data::Path|Data::Path> and
L<Data::DPath|Data::DPath>.

(Warning: B<alpha> grade comparison ahead, not yet fully verified,
only evaluated by reading the source. Speed comparison not really
benchmarked.)

 ---------------------------------------------------------------------
 Criteria             Data::Path           Data::DPath
 ---------------------------------------------------------------------
 
 real XPath syntax    no                   no
 
 ---------------------------------------------------------------------
 
 allow strange,       YES                  YES
 non-xml but
 perl-like            although
 hash keys            limited,
                      see next
 ---------------------------------------------------------------------
 
 allows special       no                   YES
 chars of own
 path syntax in                            you can quote everything
 hash keys
 ("/[]|*.")
 
 ---------------------------------------------------------------------
 
 call subs in         YES                  no
 data structure,
 like:
 /method()
 ---------------------------------------------------------------------
 
 callbacks on         YES                  no
 not found keys
 
 ---------------------------------------------------------------------
 
 element "//"         no                   YES
 for "ANYWHERE"
 (//foo/bar)
 
 ---------------------------------------------------------------------
 
 element "."          no                   YES
 for "NOSTEP" or
 "actual position"
 (/.[filter expr])
 
 ---------------------------------------------------------------------
 
 element ".."         no                   YES
 for "PARENT"
 (//foo/..)
 
 ---------------------------------------------------------------------
 
 element "::ancestor" no                   YES
 for "ANCESTOR"
 (//foo/::ancestor)
 
 ---------------------------------------------------------------------
 
 element              no                   YES
 "::ancestor-or-self"
 
 ---------------------------------------------------------------------
 
 element "*"          no                   YES
 for "ANYSTEP" or
 "all subelements"
 (/foo/*)
 
 ---------------------------------------------------------------------
 
 array access         YES                  YES
 like /foo[4]
                      although             including negative indexes
                      limited              and whitespace awareness
 
 ---------------------------------------------------------------------
 
 complex              no                   YES
 filter expressions
 like                                      full Perl expressions
 /foo[size == 3] or                        plus sugar functions
 /.[isa("Foo::Bar")]
 
 ---------------------------------------------------------------------
 
 works with           YES                  YES
 blessed subelements
 
 ---------------------------------------------------------------------