enum types that are defined as nested types are always implicitly static (see JLS §8.9. Enums) You can’t have a static nested type inside a non-static one (a.k.a an “inner class”, see JLS §8.1.3. Inner Classes and Enclosing Instances). Therefore you can’t have an enum inner type inside a non-static nested type.
The reason it has 9 numbers is because python treats [x + y for x in l2 for y in l1 ] similarly to for x in l2: for y in l1: x + y ie, it is a nested loop
Indeed, you are correct. This is described in detail in the Expressions section in the Python Language Reference. Note especially the order of nesting of several fors in a single list comprehension, which is always left-to-right: >>> matrix = [[1, 2], [3, 4]] >>> [item for item in row for row in matrix] # oops! … Read more
The compiler told you exactly what to do. Write typename before ptrModel<std::vector<Data> >::Type, like so: typedef typename ptrModel<std::vector<Data> >::Type Type; The reason for this requirement is that the compiler doesn’t at this point know whether ptrModel<std::vector<Data> >::Type describes a member variable or a nested type. It can’t even figure that out by looking at the … Read more
The code object is pre-compiled so that part has no overhead. The function object gets built on every invocation — it binds the function name to the code object, records default variables, etc. Executive summary: It’s not free. >>> from dis import dis >>> def foo(): def bar(): pass return bar >>> dis(foo) 2 0 … Read more
Put in a function, short and fast (no recursion). var createNestedObject = function( base, names ) { for( var i = 0; i < names.length; i++ ) { base = base[ names[i] ] = base[ names[i] ] || {}; } }; // Usage: createNestedObject( window, [“shapes”, “triangle”, “points”] ); // Now window.shapes.triangle.points is an empty … Read more
You need to use the Dot Notation for the arrays. That is, you should replace the $ with the zero-based index of the element you’re trying to update. For example: db.users.update ({_id: ‘123’}, { ‘$set’: {“friends.0.emails.0.email” : ‘2222’} }); will update the first email of the first friend, and db.users.update ({_id: ‘123’}, { ‘$set’: {“friends.0.emails.1.email” … Read more
Use a nested class when the class you are nesting is only useful to the enclosing class. For instance, nested classes allow you to write something like (simplified): public class SortedMap { private class TreeNode { TreeNode left; TreeNode right; } } You can make a complete definition of your class in one place, you … Read more
Figured out the answer. The trick was: @topic.linkers.build.build_article That builds the linkers, then builds the article for each linker. So, in the models: topic.rb needs accepts_nested_attributes_for :linkers linker.rb needs accepts_nested_attributes_for :article Then in the form: <%= form_for(@topic) do |topic_form| %> …fields… <%= topic_form.fields_for :linkers do |linker_form| %> …linker fields… <%= linker_form.fields_for :article do |article_form| %> … Read more