Choosy Imports

In Flow-Wing, the bring statement can selectively import specific exposed items from a file or module. This mechanism is known as choosy imports, where only the necessary components are imported from an external file. This helps in avoiding namespace pollution and enhances code readability and maintainability by importing only what is required.

Syntax

bring {item1, item2, ..., itemN} from "path_to_file"

-item1, item2, ..., itemN: These are the specific variables, types, classes, or functions that are exposed in the source file and imported into the current file. +globalCount, handleData: These are the specific variables, types, classes, or functions that are exposed in the source file and imported into the current file. -path_to_file: This is the relative path to the file containing the exposed definitions.

Examples

bring {globalCount, handleData} from "dependencies.fg"

print(globalCount) /; Using imported variable
handleData(99)     /; Using imported function

In the above example, only globalCount and handleData are imported from dependencies.fg, meaning that other exposed items from dependencies.fg (e.g., Printer, defaultComplexType) are not accessible in the current file.

Example 2

• dependencies.fg

We use expose keyword to make the exposed items available to other files.

expose var globalCount:int = 2

expose type StringWrapper = {
  value:str 
}

expose type ComplexType = {
  id:int,
  data:StringWrapper[2]
}

expose var defaultComplexType:ComplexType = {}

expose var complexTypeArray:ComplexType[2] 

expose class Printer {
  var count:int 
  var complexData:ComplexType  

  init(complexData:ComplexType) -> nthg {
      self.complexData = complexData 
  }

  printData() -> nthg {
      print(self.complexData)
  }
}

expose fun handleData(input:int) -> nthg {
  var printerInstance:Printer = new Printer({data:[{value:"Hello"}]})
  print("Printer Instance Data: ", printerInstance.complexData)

  print("Global Default Complex Type: ", defaultComplexType)

  print("Input Value: ", input)
}

• choose_example.fg

bring {globalCount, defaultComplexType, complexTypeArray, handleData, Printer} from "file1.fg"

print(globalCount)

print(defaultComplexType)

print(complexTypeArray)

handleData(88)

var customComplexType:ComplexType  

customComplexType = {id:2}
print("Custom Complex Type: ", customComplexType)

var printerInstance:Printer = new Printer({})
printerInstance.printData()