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Results

Results define the outputs of some declaration when it is called. Here is an example:

result: Int

Here is a breakdown of the syntax:

  • The name of the result (here result). This can be any combination of upper- and lowercase letters, underscores, and numbers, as long as it does not start with a number. However, we suggest to use lowerCamelCase for the names of parameters.
  • A colon.
  • The type of the parameter (here Int).

Complete Example

Let us now look at a full example of a segment called doSomething with two results:

segment doSomething() -> (result1: Int, result2: Boolean) {
    // ...
}

The interesting part is the list of results, which uses the following syntactic elements:

  • An arrow ->.
  • An opening parenthesis.
  • A list of results, the syntax is as described above. They are separated by commas. A trailing commas is permitted.
  • A closing parenthesis.

Shorthand Version: Single Result

In case that the callable produces only a single result, we can omit the parentheses. The following two declarations are, hence, equivalent:

segment doSomething1() -> (result: Int) {}

segment doSomething2() -> result: Int {}

Shorthand Version: No Results

In case that the callable produces no results, we can usually omit the entire results list. The following two declarations are, hence equivalent:

segment doSomething1() -> () {}

segment doSomething2() {}

The notable exception are callable types, where the result list must always be specified even when it is empty.

Corresponding Python Code

Note: This section is only relevant if you are interested in the stub language.

Results must be ordered the same way in Python as they are in Safe-DS. Moreover, the Safe-DS type of a result should capture the possible values of this result accurately. Ideally, the Python result should also have a matching type hint.

Since Python results do not have a name, the names of Safe-DS results can be arbitrary. Naturally, a name should be chosen that captures the purpose of the result.