Move 'var/val parameter may not be call-by-name' to error case class #2447
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smarter
reviewed
May 16, 2017
| val msg = s"${if (mutable) "`var'" else "`val'"} parameters may not be call-by-name" | ||
| val kind = "Syntax" | ||
| val explanation = | ||
| hl"""Parameters of classes and traits may no be call-by-name. In case you |
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They can be as long as they don't have a getter e.g, this compiles:
class Foo(x: => Int)There was a problem hiding this comment.
Yes, will be more specific.
smarter
reviewed
May 16, 2017
| |want the parameter to be evaluated on demand, consider using a function | ||
| |and a lazy value in the class such as | ||
| | ${s"class MyClass(${name}Tick: () => String) {"} | ||
| | ${s" lazy val $name = ${name}Tick"} |
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But that's different from what a by-name would do, the closest thing would be to use a def, not a lazy val:
class MyClass(fooFun: () => Int)) {
def foo() = fooFun()
}There was a problem hiding this comment.
Or even:
class MyClass(myFoo: => Int) {
def foo() = myFoo
}There was a problem hiding this comment.
Ok, that's better. Will update.
… improved explanation
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@felixmulder One more and I call it a day.