StringContext (original) (raw)

scala.StringContext

See theStringContext companion object

This class provides the basic mechanism to do String Interpolation. String Interpolation allows users to embed variable references directly in *processed* string literals. Here's an example:

val name = "James"
println(s"Hello, $name")  // Hello, James

Any processed string literal is rewritten as an instantiation and method call against this class. For example:

is rewritten to be:

StringContext("Hello, ", "").s(name)

By default, this class provides the raw, s and f methods as available interpolators.

To provide your own string interpolator, create an implicit class which adds a method to StringContext. Here's an example:

implicit class JsonHelper(private val sc: StringContext) extends AnyVal {
  def json(args: Any*): JSONObject = ...
}
val x: JSONObject = json"{ a: $a }"

Here the JsonHelper extension class implicitly adds the json method to StringContext which can be used for json string literals.

Value parameters

parts

The parts that make up the interpolated string, without the expressions that get inserted by interpolation.

Attributes

Companion

object

Source

StringContext.scala

Graph

Supertypes

Members list

The formatted string interpolator.

It inserts its arguments between corresponding parts of the string context. It also treats standard escape sequences as defined in the Scala specification. Finally, if an interpolated expression is followed by a parts string that starts with a formatting specifier, the expression is formatted according to that specifier. All specifiers allowed in Java format strings are handled, and in the same way they are treated in Java.

For example:

val height = 1.9d
val name = "James"
println(f"$name%s is $height%2.2f meters tall")  // James is 1.90 meters tall

Value parameters

`args`

The arguments to be inserted into the resulting string.

Attributes

Throws

IllegalArgumentException if the number of parts in the enclosing StringContext does not exceed the number of arguments arg by exactly 1.

if a parts string contains a backslash (\) character that does not start a valid escape sequence. Note: The f method works by assembling a format string from all the parts strings and using java.lang.String.format to format all arguments with that format string. The format string is obtained by concatenating all parts strings, and performing two transformations:

Let a _formatting position_ be a start of any parts string except the first one. If a formatting position does not refer to a % character (which is assumed to start a format specifier), then the string format specifier %s is inserted. 2. Any % characters not in formatting positions must begin one of the conversions %% (the literal percent) or %n (the platform-specific line separator).

Source

StringContext.scala

The raw string interpolator.

It inserts its arguments between corresponding parts of the string context. As opposed to the simple string interpolator s, this one does not treat standard escape sequences as defined in the Scala specification.

For example, the raw processed string raw"a\nb" is equal to the scala string "a\\nb".

Note: Even when using the raw interpolator, Scala will process Unicode escapes. Unicode processing in the raw interpolator is deprecated as of scala 2.13.2 and will be removed in the future For example:

scala> raw"\u005cu0023"
res0: String = #

Value parameters

`args`

The arguments to be inserted into the resulting string.

Attributes

Throws

IllegalArgumentException if the number of parts in the enclosing StringContext does not exceed the number of arguments arg by exactly 1.

Note

The Scala compiler may replace a call to this method with an equivalent, but more efficient, use of a StringBuilder.

Source

StringContext.scala

The simple string interpolator.

It inserts its arguments between corresponding parts of the string context. It also treats standard escape sequences as defined in the Scala specification. Here's an example of usage:

val name = "James"
println(s"Hello, $name")  // Hello, James

In this example, the expression nameisreplacedwiththe‘toString‘ofthevariable‘name‘.The‘s‘interpolatorcantakethe‘toString‘ofanyarbitraryexpressionwithina‘name is replaced with the toString of the variable name. The s interpolator can take the toString of any arbitrary expression within a </annotation></semantics></math>nameisreplacedwiththe‘toString‘ofthevariable‘name‘.The‘s‘interpolatorcantakethe‘toString‘ofanyarbitraryexpressionwithina‘{} block, for example: