Feature Requests item #1618676, was opened at 2006-12-19 12:08 Message generated for change (Comment added) made by jettlogic You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=355470&aid=1618676&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None >Status: Closed Resolution: None Priority: 5 Private: No Submitted By: JettLogic (jettlogic) Assigned to: Nobody/Anonymous (nobody) Summary: Promote list comprehensions to Language Integrated Query? Initial Comment: Hi, A feature idea (shall put to mailing list discussion sometime), is to extend list comprehensions to many uses of SQL or XQuery unnecessary. The benefit of language integration over passing SQL/XQuery strings to external libraries would be making code agnostic to the source of the data: in-memory tables and trees could be queried just like a relational DB or XML. An "order by" could be more efficient than sorted(f(x) for x in y). Of course list comprehensions do much of the C#-style LINQ already, but they can't (easily) do joins or "select x from a, y from b" type queries, or return XML a la XQuery. On the library side, DBAPI helps make code independent of any particular database, and sqlite in 2.5 means in-memory tables (lists of tuples) aren't really necessary. If worthwhile, implementation would probably be best suited to PyPy. C# Example from http://en.wikipedia.org/wiki/Language_Integrated_Query var q = from o in db.Orders, c in db.Customers where o.Quality == "200" && (o.CustomerID == c.CustomerID) select new { o.DueDate, c.CompanyName, c.ItemID, c.ItemName }; ---------------------------------------------------------------------- >Comment By: JettLogic (jettlogic) Date: 2006-12-22 12:25 Message: Logged In: YES user_id=1345991 Originator: YES Oh ok, I guess it's up to the Py3k discussions then to figure out LINQ. Funny my search for "Python Language Integrated Query" didn't turn up much (at least not the Py3k list) and now my OP is #1 on Google on 2006/12/22 for the search. Though "Python LINQ" turns up: http://sayspy.blogspot.com/2006/02/why-python-doesnt-need-something-like.html I suppose there's still the efficiency of having the database doing the filter (instead of "if x > 5") and the grouping (instead of itertools.groupby()), and the joins. ---------------------------------------------------------------------- Comment By: Josiah Carlson (josiahcarlson) Date: 2006-12-22 07:59 Message: Logged In: YES user_id=341410 Originator: NO There have been various discussions about metasyntax proposals and Python, see the Python-3000 mailing list for references to LINQ. The general answer has been "no". Note that you can do much of what you want by overloading operations on standard Python objects like __or__, __and__, etc. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=355470&aid=1618676&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
