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More of Mark's suggested cleanups to basic build def page.

Havoc Pennington 2011-10-18 15:29:09 -04:00
parent 36689fd29b
commit 726d976780
1 changed files with 17 additions and 11 deletions
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28
Getting-Started/Getting-Started-Basic-Def.md

@ -77,9 +77,10 @@ scalaVersion := "2.9.1"
A `build.sbt` file is a list of `Setting`, separated by blank lines. Each
`Setting` is defined with a Scala expression.
The expressions in `build.sbt` are independent of one another, and they are
expressions, rather than complete lines of Scala code. An implication of
this is that you can't define a `val` or `object` in `build.sbt`.
The expressions in `build.sbt` are independent of one another, and
they are expressions, rather than complete Scala statements. An
implication of this is that you can't define a top-level `val`,
`object`, class, or method in `build.sbt`.
On the left, `name`, `version`, and `scalaVersion` are _keys_. A
key is an instance of `SettingKey[T]`, `TaskKey[T]`, or
@ -109,10 +110,11 @@ name := 42 // will not compile
## Keys are defined in the Keys object
Keys are just fields in an object called [Keys]. A `build.sbt` implicitly
has an `import sbt.Keys._`, so `sbt.Keys.name` can be referred to as `name`.
The built-in keys are just fields in an object called [Keys]. A
`build.sbt` implicitly has an `import sbt.Keys._`, so
`sbt.Keys.name` can be referred to as `name`.
Custom keys could also be defined in a
Custom keys may be defined in a
[[full build definition|Getting Started Full Def]] or a [[plugin|Getting Started Using Plugins]].
## Other ways to transform settings
@ -180,7 +182,7 @@ _A given key always refers to either a task or a plain setting._ That is,
"taskiness" (whether to re-run each time) is a property of the key, not the
value.
Using `:=`, you can assign a function to a task, and that function will be
Using `:=`, you can assign a computation to a task, and that computation will be
re-run each time:
```scala
@ -199,11 +201,15 @@ re-run. More on this in [[more about settings|Getting Started More About Setting
## Keys in sbt interactive mode
In sbt's interactive mode, you can type the name of any key to retrieve
the value of that key. If the key represents a task, then the task will be
executed.
In sbt's interactive mode, you can type the name of any task to
execute that task. This is why typing `compile` runs the compile
task. `compile` is a task key.
This is why typing `compile` runs the compile task. `compile` is a task key.
If you type the name of a setting key rather than a task key, the
value of the setting key will be displayed. Typing a task key name
executes the task but doesn't display the resulting value; to see
a task's result, use `show <task name>` rather than plain `<task
name>`.
In build definition files, keys are named with `camelCase` following Scala
convention, but the sbt command line uses `hyphen-separated-words`