8000 Save FAQ entry from paulp/scala-faq on abstract value troubles by Blaisorblade · Pull Request #270 · scala/docs.scala-lang · GitHub
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Merged
merged 3 commits into from
Nov 23, 2013
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Save FAQ entry from paulp/scala-faq on abstract value troubles #270

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Save entry from paulp/scala-faq
Blaisorblade Nov 23, 2013
9f9804e
Fix sectioning
Blaisorblade Nov 23, 2013
b38c07a
State problem more explicitly
Blaisorblade Nov 23, 2013
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Fix sectioning
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@Blaisorblade
Blaisorblade committed Nov 23, 2013
commit 9f9804e8e7d7f12a0207c7b3743eb844dfe4ba15
8 changes: 5 additions & 3 deletions tutorials/FAQ/initialization-order.md
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Expand Up @@ -57,9 +57,11 @@ scala.UninitializedFieldError: Uninitialized field: a.scala: 13
at C.<init>(a.scala:12)
```

### Solutions ###

Approaches for avoiding null values include:

#### Use lazy vals. ####
#### Use lazy vals ####

```scala
abstract class A {
Expand Down Expand Up @@ -94,7 +96,7 @@ An exception during initialization of a lazy val will cause the right hand side

Note that using multiple lazy vals creates a new risk: cycles among lazy vals can result in a stack overflow on first access.

#### Use early definitions. ####
#### Use early definitions ####
```scala
abstract class A {
val x1: String
Expand All @@ -120,7 +122,7 @@ class C extends {

Early definitions are a bit unwieldy, there are limitations as to what can appear and what can be referenced in an early definitions block, and they don't compose as well as lazy vals: but if a lazy val is undesirable, they present another option. They are specified in SLS 5.1.6.

#### Use constant value definitions. ####
#### Use constant value definitions ####
```scala
abstract class A {
val x1: String
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