Resource Orchestration Service:Fn::Add - Resource Orchestration Service

The built-in function Fn::Add calculates the sum of parameters of the Number type, combines parameters of the List type, or merges parameters of the Dictionary type.

Declaration

JSON

{
  "Fn::Add": [
    {k1: v1},
    {k2: v2}
  ]
}

YAML
- Syntax for the full function name:
```
Fn::Add:
  - k1: v1
  - k2: v2
```
- Syntax for the short form:
```
!Add [{k1: v1}, {k2: v2}, ...]
```

Parameters

Parameters must be arranged as a parameter set.
The parameters can be of the Number, List, or Dictionary type. A set of parameters must be of the same type. A parameter set must contain at least two parameters.

Return value

If the parameters are of the Number type, the sum of the parameter values are calculated.
If the parameters are of the List type, the parameters are combined.
If the parameters are of the Dictionary type, the parameters are merged. If parameters of the Dictionary type have the same key, the latter overwrites the former.

Examples

Parameters of the Dictionary type
```
!Add
  - key1: value1
  - key2: value2
```
In this example, {"key1": "value1", "key2": "value2"} is returned.
Parameters of the List type
```
!Add
	- - list_1_value_1
  	- list_1_value_2
  - - list_2_value_1
  	- list_2_value_2
```
In this example, ["list_1_value_1","list_1_value_2","list_2_value_1","list_2_value_2"] is returned.
Parameters of the Number type
```
!Add
 - 1
 - 2
 - 3
```
In this example, 6 is returned.