Why? What are the advantages?

Memory consumption on large data

Good point, @garak! Is this something you want to work on? We should create a separate portphp/spout repository for box/spout readers and writers.

OK

Created the repo at https://github.com/portphp/spout. @garak Please proceed by creating a PR against that repo. Feel free to add yourself as an author to the readme and composer.json. Thank you very much!

@garak Did you start an implementation ?

not yet

I noticed the array buffering in portphp/excel. The next thing I was going to work was that. If PHPOffice/Spreadsheet has some kind of iterable interface, then we could use that instead of buffering with toArray()

Of course PHPOffice has something like this. https://phpspreadsheet.readthedocs.io/en/develop/topics/accessing-cells/#looping-through-cells