CollectionIsEmptyRule.md

Collections

Using Collection.size() to test for emptiness works, but using Collection.isEmpty() or Collection.Empty makes the code more readable and can be more performant. The time complexity of any isEmpty() method implementation should be O(1) whereas some implementations of size() can be O(n).

Queries

If you want to know only whether a result or query object fetched anything from the application database, use the Empty property instead of the Count property. The value of the Empty property returns to your Gosu code faster, because the evaluation stops as soon as it counts at least one fetched item. In contrast, the value of the Count property returns to your Gosu only after counting all fetched items.

Length property

length property is usually the same as isEmpty() in performance.

isEmpty(), however states what you're actually interested in more clearly

Noncompliant Code Example

if (myCollection.size() == 0) {  // Noncompliant
  /* ... */
}

var result = policyPeriodQuery.select()
    if (result.Count == 0) {  // Noncompliant
 /* ... */
}

Compliant Solution

if (myCollection.isEmpty()) {
  /* ... */
}

if (myCollection.Empty) {
  /* ... */
}

var result = policyPeriodQuery.select()
    if (result.Empty) {
 /* ... */
}