AddRange from `await` directly

Question

I am currently returning a list of lists (List<List<string>>) from await getWorlds() and right now I am looping through each one of them, and getting the first entry in each list.

I just wonder if there is another way I can quickly add all of them directly into Worlds with .AddRange or something?

Here is my code:

var worlds = await getWorlds();
foreach (var w in worlds)
{
    Worlds.Add(w[0]);
}

Any way to shorten this to something smaller? Like Worlds = worlds.AddRange([0]); or something? I just want to get the first entry [0] and add each one to the Worlds. I'm just looking to see if there's a cleaner way of writing my code. I have not managed to find any example.

Joel Coehoorn · Accepted Answer · 2018-09-04T13:28:47.493

3

You can do this:

var worlds = await getWorlds();
Worlds.AddRange(worlds.Select(w => w[0]));

Though I don't see why the foreach was so bad.

edited Sep 04 '18 at 13:28

answered Sep 04 '18 at 13:27

Joel Coehoorn

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1

Perfect! Thank you!!!! I was just looking for best-practices. I am new in C# and I just try to write as little code as possible that does the job for me. Would it even be possible to put it all in one line? and switch `worlds.` to `await getWorlds().`? or something – Lee Cheung Sep 04 '18 at 13:28
3

@Lee The smallest amount of code is not always the best, it can make it unreadable or hard to understand. Sometimes a simple loop is the best, especially as this code is doing basically the same thing but hiding the loop from you. – DavidG Sep 04 '18 at 13:31
The main thing to remember with stuff like this is that the compiler will likely end up optimising it to the same code underneath anyway - you will almost certainly not achieve anything in terms of performance or efficiency by obsessing over this sort of thing... – GPW Sep 04 '18 at 13:34
Something like this is starting to get difficult to read: `Worlds.AddRange((await getWorlds()).SelectMany(w => w.Take(1)))`. – Enigmativity Sep 04 '18 at 13:35
I see. Thanks guys for your help and explanations! I really appreciate it! :) – Lee Cheung Sep 04 '18 at 13:38

score 2 · Answer 2 · answered Sep 04 '18 at 13:38

This is not quite what you're looking for, but you could do this to add all instances of items in all the sub-lists too, rather than just the first one.. (this will flatten the list into a single list of items)

var worlds = await getWorlds();
Worlds.AddRange(worlds.SelectMany(w=>w));

AddRange from `await` directly

2 Answers2