tuples

(I would check this out for myself, but I don't have VS2010 (yet)) Say I have 2 base interfaces: IBaseModelInterface IBaseViewInterface And 2 interfaces realizing those: ISubModelInterface : IBaseModelInterface ISubViewInterface : IBaseViewInterface If I define a Tuple<IBaseModelInterface, IBaseViewInterface> I would like to set that based on the result of a factory that returns Tuple<ISubModelInterface, ISubViewInterface> . In C# 3 I can't do this even though the sub interfaces realize the base interfaces. And I'm pretty sure C# 4 lets me do this if I was using IEnumerable<IBaseModelInterface

I'm using a std::tuple and defined a class enum to somehow "naming" each of the tuple's fields, forgetting about their actual indexes. So instead of doing this: std::tuple<A,B> tup; /* ... */ std::get<0>(tup) = bleh; // was it 0, or 1? I did this: enum class Something { MY_INDEX_NAME = 0, OTHER_INDEX_NAME }; std::tuple<A,B> tup; /* ... */ std::get<Something::MY_INDEX_NAME> = 0; // I don't mind the actual index... The problem is that, as this compiled using gcc 4.5.2, I've now installed the 4.6.1 version, and my project failed to compile. This snippet reproduces the error: #include <tuple>

I tried to find the available methods but couldn't find it. There is no contains . Should I use index ? I just want to know if the item exists, don't need the index of it. You use in . if element in thetuple: #whatever you want to do. if "word" in str(tuple): # You can convert the tuple to str too i has the same problem and only worked to me after the convert str() Be careful with that: return Oops. use Set: d= {...} def simha(): d = ('this_is_valid') b = 'valid' if b in d: print("Oops!!!!!") simha() 来源： https://stackoverflow.com/questions/17920147/how-to-check-if-a-tuple-contains-an-element

I have following method that I select all the ids from table and append them to a list and return that list. But when execute this code I end up getting tuple indicies must be integers... error. I have attached the error and the print out along with my method: def questionIds(con): print 'getting all the question ids' cur = con.cursor() qIds = [] getQuestionId = "SELECT question_id from questions_new" try: cur.execute(getQuestionId) for row in cur.fetchall(): print 'printing row' print row qIds.append(str(row['question_id'])) except Exception, e: traceback.print_exc() return qIds Printing what

I am a bit puzzled by the following tuple business: int testint = 1; float testfloat = .1f; std::tie( testint, testfloat ) = std::make_tuple( testint, testfloat ); std::tuple<int&, float&> test = std::make_tuple( testint, testfloat ); With std::tie it works, but assigning directly to the tuple of references doesn't compile, giving "error: conversion from ‘std::tuple<int, float>’ to non-scalar type ‘std::tuple<int&, float&>’ requested" or "no suitable user-defined conversion from std::tuple<int, float> to std::tuple<int&, float&>" Why? I double checked with the compiler if it's really the same

I need to combine a string along with a list of strings into a tuple so I can use it as a dictionary key. This is going to be in an inner loop so speed is important. The list will be small (usually 1, but occasionally 2 or 3 items). What is the fastest way to do this? Before: my_string == "foo" my_list == ["bar", "baz", "qux", "etc"] After: my_tuple == ("foo", "bar", "baz", "qux", "etc") (Note: my_list must not be altered itself). I can't speak for performance, but this is definitely the simplest I can think of: my_tuple = tuple([my_string] + my_list) The straightforward way is simply my_tuple