StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
text
Body
copied!<p>Unless I'm misreading you, your question may be caused by a misunderstanding.. Nothing ever returns an IEnumerable. The first case returns an Enumerator, which implements foreach, allowing you to get instances of MyClass, one at a time. It, (the function return value) is typed as IEnumerable to indicate that it supports the foreach behavior (and a few others) </p> <p>The second function actually returns a List, which of course also supports IEnumerable (foreach behavior). But it is an actual concrete collection of MyClass Objects, created by the method you called (the second one) </p> <p>The first method doesn't return any MyClass Objects at all, it returns that enumerator object, which is created by the dotNet framework and coded behind the scenes to instantiate a new MyClass object each time you iterate against it.</p> <p>EDIT: More detail A more important distinction is whether or not you want the items to be statefully held in place for you within the class, while you iterate, or whether you want them created for you when you iterate.</p> <p>Another consideration is.. are the items you wish returned to you already in existence somewhere else? i.e., is this method going to iterate through a set (or filtered subset) of some existing collection? or is it creating the items on the fly? if the latter, does it <strong><em>matter</em></strong> if the item is the exact same instance each time you "get" it? For objects defined t orepresent things that could be called an <em>entity</em> - ssomething with a defined <em>identity</em>, you probably want successive fetches to return the same instance. </p> <p>But maybe another instance with the same state is totally equivilent? (This would be called a <em>value type</em> object, like a telephone Number, or an address, or a point on the screen. Such objects have no identity except that implied by their state. In this latter case, it doesn't matter if the enumerator returns the same instance or a newly created identical copy each time you "get" it... Such objects are generally immutable, they are the same, they stay the same, and they function identically. </p>

Querying!

Guidance

An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload