How to create an anonymous array of object references

Question

I've inherited some code I'd like to DRY up into to 2 loops.

The outer loop iterates over checkBoxeList object. The inner loop checks all the boxes.

CheckBoxList[] DefaultLists = { ScanDefaultTasks, BehDefaultTasks,MEGDefaultTasks,DefaultQuestionnaires };
for (int i = 0; i < DefaultLists.Count (); i++) {
    for (int j = 0; i < DefaultLists[i].Items.Count; j++)
    {
        DefaultLists[i].Items[i].Selected = true;
    }
}

How could DefaultList be built such that it stores references to each of the checkBoxList objects?

How should these references be called?

It looks like one solution is to build a "box" class. This pattern occurs a few times, in most places duplicating greater lengths of redundant code. Building a class for each instance seems like overkill.

The original looks like

for (int i = 0; i < ScanDefaultTasks.Items.Count; i++)
{
    ScanDefaultTasks.Items[i].Selected = true;
}
for (int i = 0; i < BehDefaultTasks.Items.Count; i++)
{
    BehDefaultTasks.Items[i].Selected = true;
}
for (int i = 0; i < MEGDefaultTasks.Items.Count; i++)
{
    MEGDefaultTasks.Items[i].Selected = true;
}
for (int i = 0; i < DefaultQuestionnaires.Items.Count; i++)
{
    DefaultQuestionnaires.Items[i].Selected = true;
}

Maybe I don't get it, but what's wrong with `var DefaultLists = new List(){ ScanDefaultTasks, BehDefaultTasks,MEGDefaultTasks,DefaultQuestionnaires };`? — Konrad Kokosa, Jan 09 '14 at 21:54
@KonradKokosa like the CheckBoxList[] construction, the page hangs until timeout. Why, I don't understand yet. — Will, Jan 09 '14 at 21:58

score 1 · Accepted Answer · answered Jan 09 '14 at 21:59

DefaultLists is an array that stores references to the contained CheckBoxLists. So I do not see a problem there. The only problem I can spot in your sample is that you use i where you should use j in the inner loop:

CheckBoxList[] DefaultLists = { ScanDefaultTasks, BehDefaultTasks,MEGDefaultTasks,DefaultQuestionnaires };
for (int i = 0; i < DefaultLists.Count (); i++) {
    for (int j = 0; i < DefaultLists[i].Items.Count; j++)
    {
        DefaultLists[i].Items[j].Selected = true;
    }
}

I've changed the second i to a j in this line:

DefaultLists[i].Items[j].Selected = true;

In order to simplify things a bit, you could also use for each for the loops:

CheckBoxList[] DefaultLists = { ScanDefaultTasks, BehDefaultTasks,MEGDefaultTasks,DefaultQuestionnaires };
foreach(var cbl in DefaultLists)
    foreach(var item in cbl.Items)
        item.Selected = true;

also needed to change an i->j inside the for loop conditional. given that I can't distinguish between the indexes I choose, foreach seems like a much better solution! — Will, Jan 09 '14 at 22:09

score 0 · Answer 2 · answered Jan 09 '14 at 22:04

You could possibly do something like this:

foreach(var item in new CheckBoxList[]{
                             ScanDefaultTasks, 
                             BehDefaultTasks,
                             MEGDefaultTasks,
                             DefaultQuestionnaires}
                      .SelectMany(l => l.Items))
  item.Selected = true;

How to create an anonymous array of object references

2 Answers2