美元符号在scala中做了什么

Question

当我在这里阅读火花源代码时,我看到了类似的代码$(a_variable).这是什么意思？

我在这里复制代码:

  final val blockSize: IntParam = new IntParam(this, "blockSize",
    "Block size for stacking input data in matrices. Data is stacked within partitions." +
      " If block size is more than remaining data in a partition then " +
      "it is adjusted to the size of this data. Recommended size is between 10 and 1000",
    ParamValidators.gt(0))

  /** @group getParam */
  final def getBlockSize: Int = $(blockSize)

Answer 1

这不是特殊的Scala语法,它是一个方法名称.在Scala中$是一个合法的标识符.该方法继承自org.apache.spark.ml.param.Param特征.

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