Creating specific lambda expression

Question

I've been working on this code for a while now, and am very slow at this point. I don't know if the answer is obvious, but I haven't been able to think of a way to convert this bit:

foreach (Item i in stockList)
{
    if (i == order.OrderItem)
        i.ChangeStock(order.NumberOfItems);
}
outStandingOrders.Remove(order);

into a lambda expression. The best I could come up with is

stockList.ForEach(i => i == order.OrderItem)

(Don't know where to go from here)

There is also only ever one item in stockList that is equal to order.OrderItem.

Any help would be hot

Thanks!

It should be cleaner and I don't know how, so that makes me curious. Based off of the documentation it should be possible. — user3421751
– user3421751, Commented Apr 30, 2014 at 8:00
I thought it would be cleaner, I guess that's not the case. Normally it cleans up fairly well. I'm also trying to become more familiar with lambdas. — user3421751
– user3421751, Commented Apr 30, 2014 at 8:05

Konrad Kokosa · Accepted Answer · 2014-04-30 08:00:34Z

4

Basing on your information that "There is also only ever one item in stockList that is equal to order.OrderItem", I would write it simply:

 var item = stockList.FirstOrDefault(i => i == order.OrderItem);
 if (item != null)
 {
     item.ChangeStock(order.NumberOfItems);    
 }

answered Apr 30, 2014 at 8:00

Konrad Kokosa

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6 Comments

Milan Halada Over a year ago

and what if there are multiple orderitems in stocklist? This would work only for first

user3421751 Over a year ago

There aren't multiple Orders in stockList.

Milan Halada Over a year ago

oh, missed that line ^^

sloth Over a year ago

If there's only ever excatly one matching item, I would use Single (or SingleOrDefault if there can be zero matching items). This would make the intent clearer and throw an expection if there are more than a single matching item. If it's wrong if there are more than one matching item, you want to know it as early as possible.

Scordo Over a year ago

I missed that line, too :-D

|

Scordo · Accepted Answer · 2014-04-30 08:06:59Z

4

stockList.FindAll(i => i == order.OrderItem)
.ForEach(i => i.ChangeStock(order.NumberOfItems));

Untested, just typed ^^

edited Apr 30, 2014 at 8:06

answered Apr 30, 2014 at 7:59

Scordo

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2 Comments

user3421751 Over a year ago

Works like a charm, although it needed one more parenthesis at the end.

Scordo Over a year ago

Added the missing parenthesis

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