更新时间:2023-09-28 23:10:52
Scala有一个编译器选项 -Xprint:typer
,您可以使用它来获取内部使用的后期打印源代码。
Scala has a compiler option -Xprint:typer
, which you can use to get the "post-typing source code that it uses internally".
scala -Xprint:typer -e 'case class Foo(a: String, b: Int)'
你看到的是:
Here you see something like:
override def hashCode(): Int = ScalaRunTime.this._hashCode(Foo.this);
override def toString(): String = ScalaRunTime.this._toString(Foo.this);
override def equals(x$1: Any): Boolean = Foo.this.eq(x$1).||(x$1 match {
case (a: String,b: Int)this.Foo((a$1 @ _), (b$1 @ _)) if a$1.==(a).&&(b$1.==(b)) => x$1.asInstanceOf[this.Foo].canEqual(Foo.this)
case _ => false
});
但是,这并不能告诉你如何生成hashCode。下面是源代码:
But, this doesn't tell you how hashCode is generated. Here's the source for that:
def _hashCode(x: Product): Int = {
var code = x.productPrefix.hashCode()
val arr = x.productArity
var i = 0
while (i < arr) {
val elem = x.productElement(i)
code = code * 41 + (if (elem == null) 0 else elem.hashCode())
i += 1
}
code
}
在本例中,等号模式匹配的第一种情况将是:
And, in this example, the first case of the equals pattern matching would just be:
case that: Foo => this.a == that.a && this.b == that.b