There are ways of reading PDF files, modifying them, them printing it back as a PDF file. They are ugly, prone to issues (like randomly not working), and are extremely difficult to work with.

It is EXTREMELY simply to work with (the soon-to-be-released version of) PDF::Template. Creating the XML template is actually easier than creating the PDF. If you already have the PDF, converting it to the XML layout is simple, too. (And, as a new co-author of PDF::Template, I would be delighted to help you convert your current PDFs to the appropriate XML.)

Also, we are looking at (in the not-too-distant future) creating a DBI-like Document namespace which would handle reading from and writing to PDFs (as well as PS, TeX, and other similar document layout formats). That would definitely solve your issue. And, if you (or anyone else) wanted to help, we're just working through requirements right now. :-)

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.