When it makes sense, define a field like this to be lazy, meaning it won’t be evaluated until it is accessed. assign the xml field to the result of the load method In a similar way, you can assign a class field to the results of a method or function: Therefore, compiling and running this example will either print the contents of the file, or the “Error happened” message from the catch block. Lines = io.omFile('/etc/passwd').getLines.mkStringĬase e: Exception => lines = 'Error happened'īecause the assignment of the code block to the text field and the println statement are both in the body of the Foo class, they are in the class’s constructor, and will be executed when a new instance of the class is created. set 'text' equal to the result of the block of code In the following example, the field text is set equal to a block of code, which either returns (a) the text contained in a file, or (b) an error message, depending on whether the file exists and can be read: Optionally, define the field as lazy if the algorithm requires a long time to run. Set the field equal to the desired block of code or function. You want to initialize a field in a Scala class using a block of code, or by calling a function. This is Recipe 4.8, “How to assign a Scala class field to a block or function.” Problem

This is an excerpt from the 1st Edition of the Scala Cookbook (partially modified for the internet). show more info on classes/objects in repl.

Kotlin by lazy with parameter