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May 14, 2018
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Document meaning of constant expressions #4527

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Document meaning of constant expressions
Blaisorblade May 14, 2018
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Blaisorblade May 14, 2018
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15 changes: 10 additions & 5 deletions docs/docs/reference/inline.md
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Expand Up @@ -29,7 +29,8 @@ inlined at the point of use. Example:
The `Config` object contains a definition of an `inline` value
`logging`. This means that `logging` is treated as a constant value,
equivalent to its right-hand side `false`. The right-hand side of such
an inline val must itself be a constant expression. Used in this way,
an inline val must itself be a [constant
expression](#the-definition-of-constant-expression). Used in this way,
`inline` is equivalent to Java and Scala 2's `final`. `final` meaning
"constant" is still supported in Dotty, but will be phased out.

Expand Down Expand Up @@ -124,11 +125,15 @@ it in backticks, i.e.

@`inline` def ...

### The definition of constant expression

Right-hand sides of inline values and of arguments for inline parameters
must be constant expressions in the sense defined by the [SLS §
6.24](https://www.scala-lang.org/files/archive/spec/2.12/06-expressions.html#constant-expressions),
including "platform-specific" extensions such as constant folding of
pure numeric computations.

### Reference

For more info, see [PR #1492](https://github.com/lampepfl/dotty/pull/1492) and
[Scala SIP 28](http://docs.scala-lang.org/sips/pending/inline-meta.html)



[Scala SIP 28](http://docs.scala-lang.org/sips/pending/inline-meta.html).