A "non-text based" template is usually quite hard, because usually, binary file formats tend to encode the length of fields somewhere. Your best approach is to read an Excel file using Spreadsheet::ParseExcel, replace all the values/loops within cells, and then write it out again using Spreadsheet::WriteExcel.

As such it isn't possible to template a binary Excel file in the same way that you would template a text file.

Hence the route that Excel::Template and Spreadsheet::WriteExcel::FromXML take where the tempate file is text or XML based and the backend uses Spreadsheet::WriteExcel to create the Excel binary file.

The newer xlsx Excel files from Excel 2007 onwards are XML files contained in a zip file and are more suitable for TT style templating.

As an aside I am working on an xlsx writer module that will eventually read and rewrite files as well so that it will be possible to use an existing file as a template (although not in the TT sense). However, that work is still at an early stage.

--
John.

Since the Excel XML format is a well-behaved, full featured (and thoroughly documented) format that Excel can both read and write, I strongly suggest that you use this approach.   If you are generating “stock” outputs (e.g. reports) in Excel format, templates are a reliable way to do it.   (I did this recently for Excel 2003 and impressed a lot of my client’s folks.)   If you need to do more advanced things, any XML-oriented package would be suitable and efficient.

It seemed to me that MS has done their homework on this one.   It’s a good, clean design that can handle formulas, formatting, you name it.   And I think that there’s a formal DTD for it, as well.

The final result is “exactly as the user expects.”   They do not have to do anything special, afaik, to handle the file.   Excel sees what the file contains and, “it just works.™”   In fact, I believe that their new .xslx format is XML-based behind the scenes.

Every Excel version since (I think...) 2003 has defined a very well thought-out XML format, which is easy to build using a template.

AFAIK, if a file with the extension “.XLS” actually turns out to contain XML content ... “it just works.”

I have used a similar strategy to populate a (live!) Excel spreadsheet within a generated web-page.   As long as the MIME-type is correct, it works.

I don't know what you need it for, so I've to ask: would your code equally benefit from a templating system on openoffice spreadsheet?

First and foremost, thanks to everybody for you comments!

I believe a little clarification regarding the "binary" format would be of use. My idea was to be able to have a binary excel template, read it using Spreadsheet::ParseExcel and feed text and variables to TT for processing and then Spreadsheet::WriteExcel to a new binary file. My idea was to plugin where TT reads and writes a text file and convert "read next line" to "read next row" and "write line" to "write row".

Although the idea of marking and escaping the binary file directly seems like a nice candidate for the Obfuscation forum... my idea is to have a template that resembles the processed file for ease of template creation.

My final solution will be to convert Excel to text including a little markup that identifies columns ends and rows ends. Since a way to have markup "outside" rows and columns will arise I will use TT markup in comments that will be converted to text putting it "before" the column marker. Then run TT on it and read through the text converting the original marks to "next column" and "next row"

Thanks again to everybody.

gbarco:

Given your proposed usage, then I'd use XML, as mentioned in earlier posts. That way, you'd be able to:

1. produce your template easily (generate it manually, or create a spreadsheet in Excel, save as .xlsx and edit it into shape),
2. fill it out without jumping through flaming hoops (text files are *much* easier to munge, and XML files may be even easier with the various XML packages available on CPAN),
3. and be able to have widespread usage. (Since XML is easy enough to read and manipulate, people using tools other than Excel may be able to use your files.

Of course, that's just my $local_currency/50...

...roboticus