in reply to Accessing the __DATA__ blocks of other packages

No need for eval or other heavy artillery.
package TMPL; sub fodus { local $/; my $out = <($main::{+(caller)[0]."::"}->{DATA})>; # ... return $out; }
The key here is that Perl makes the symbol table of each package available as a hash called %%packagename:: - with %main:: containing keys for all packages including itself, the value being a glob pointing in turn to that package's symbol table. So I use %main:: to get the glob to the caller's package, then dereference it as a hash, fishing the DATA key from it in turn.

Makeshifts last the longest.