This is a bad idea. This approach requires that the connection is open the whole time until the last row is read, and outside the DAO layer you never know when it will happen, and you also seem to leave the resultset open and risk resource leaks and application crashes in the case the connection … Read more
Pointers into an array can be used as random access iterators. There needs to be some consistent way to get these types both for pointers (which obviously can’t have the types declared as nested types, since only classes can have nested types) and for class-type iterators. The traits class template provides this consistent way. The … Read more
There is no need to use the c’tor taking a range. std::string has a constructor that operates in terms of std::string_view, number 10 in the list. The effect of which is template < class T > explicit basic_string( const T& t, const Allocator& alloc = Allocator() ); Implicitly converts t to a string view sv … Read more
No, a vector is not an iterator. But it implements the trait IntoIterator, which the for loop uses to convert the vector into the required iterator. In the documentation for Vec you can see that IntoIterator is implemented in three ways: for Vec<T>, which is moved and the iterator returns items of type T, for … Read more
request.FILES gives you binary files, but the csv module wants to have text-mode files instead. You need to wrap the file in a io.TextIOWrapper() instance, and you need to figure out the encoding: from io import TextIOWrapper f = TextIOWrapper(request.FILES[‘filename’].file, encoding=request.encoding) It’d probably be better if you took the charset parameter from the Content-Type header … Read more
I want to ignore all Err values Since Result implements IntoIterator, you can convert your Vec into an iterator (which will be an iterator of iterators) and then flatten it: Iterator::flatten: vec.into_iter().flatten().collect() Iterator::flat_map: vec.into_iter().flat_map(|e| e).collect() These methods also work for Option, which also implements IntoIterator. You could also convert the Result into an Option and … Read more
Use continue. for i in xrange(value): if condition: continue If you want to force your iterable to skip forwards, you must call .next(). >>> iterable = iter(xrange(100)) >>> for i in iterable: … if i % 10 == 0: … [iterable.next() for x in range(10)] … [1, 2, 3, 4, 5, 6, 7, 8, 9, … Read more
Use reverse_iterator instead of iterator. Use rbegin() & rend() instead of begin() & end(). Another possibility, if you like using the BOOST_FOREACH macro is to use the BOOST_REVERSE_FOREACH macro introduced in Boost 1.36.0.
I don’t think there was ever an actual decision to exclude iterators from bitset. Rather, bitset is one of the classes that predates the proposal to add the original Standard Template Library to the C++ standard. When it was designed, essentially none of the standard library included iterators. Then, Stepanov’s library was proposed for addition, … Read more
With C++, the only way to iterate through enums is store them in an array and iterate through the same. The main challenge is how to track the same order in the enum declaration and the array declaration? You can automate the way you order them in the enum as well as array. I feel … Read more