On Sun, Dec 15, 2019 at 6:40 AM David Mertz <mertz@gnosis.cx> wrote:
Yes, of course. I was just trying to illustrate using next() in a non-artificial way. In real code (but truthfully, probably not in my quick "one off" scripts) I write
lines = get_lines_file_or_elswhere(resource) header = next(lines, sentinel) if looks_like_header(header): for line in lines: ...
Hmm, interesting -- so this means that you do write code expecting a generic iterator, rather than a file-like object. I can't say I've ever done that, nor seem anyone else to that. I'm curious: what other iterators might this code be expected to work with? (that is, a list of lines, as returned by file.readlines() would not work --you'd have to wrap it in iter() first... But apparently it reflects the move that Python has been making toward being all about iterators. I think first() would be a help mostly to folks that DON'T think primarily in terms of iterators. And frankly, I think that is a population Python should strive to support. For the record, I write a lot of code that looks like: data_file = get_lines_file_(resource) header = data_file.readline() if looks_like_header(header): for line in data_file: ... That is, I'm always expecting a file-like object, rather than a generic iterator. That may be because I developed habits long before files were iterators.... BTW: this has been a REALLY LONG thread -- I think it's time for a concrete proposal to be written up, sonce it appears we're not all clear on what we're talking about. For my part I think a first() function would be nice, an am open to a couple variations, so someone with a stronger opinion should propose something. Tim: what version do you have in mind? -CHB -- Christopher Barker, PhD Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython