Efficient Key Existence Check in Multiple Maps

In Go, it is common to work with maps, which are efficient data structures for retrieving key-value pairs. However, the developer provided code demonstrates the need to check for the existence of a key in two separate maps. The question remains whether this process can be made more concise.

As explained in the answer, using the special v, ok := m[k] form in Go for checking key existence is limited to single-variable assignments. Therefore, combining the two checks into one if condition using this form is not feasible.

However, there are alternative approaches to achieve the desired functionality:

1. Tuple Assignment:
   If the value type of the map is an interface type and you can ensure that the nil value is not used, you can perform tuple assignment using two index expressions:

   if v1, v2 := m1["aaa"], m2["aaa"]; v1 != nil && v2 != nil {
       // ...
   }

2. Helper Function:
   A helper function can be created to perform the key existence check in both maps and return the results:

   func idx(m1, m2 map[string]interface{}, k string) (
       v1, v2 interface{}, ok1, ok2 bool) {
   
       v1, ok1 = m1[k]
       v2, ok2 = m2[k]
       return
   }

   This function can then be used as follows:

   if v1, v2, ok1, ok2 := idx(m1, m2, "aaa"); ok1 && ok2 {
       // ...
   }

These approaches allow for a concise and efficient check for the existence of a key in multiple maps within a single conditional statement.