Context
Related Doc:
package context
An environment with key bound to value; lookups for other keys
are forwarded to next.
An environment without key.
An environment without key. Lookups for other keys
are forwarded to next.
Concatenate two environments with left-hand side precedence.
An empty environment.
An empty environment. No keys are present.
Retrieve the current definition of a key.
Retrieve the current definition of a key.
NoSuchElementException when the key is undefined
in the current request-local context.
Tells whether key is defined in the current request-local
context.
Retrieve the current definition of a key, but only if it is defined in the current request-local context.
Retrieve the current definition of a key if it is defined.
Retrieve the current definition of a key if it is defined.
If it is not defined, orElse is evaluated and returned.
Bind two keys and values in the scope of fn.
Bind value to key in the scope of fn.
Clears all bindings in the scope of fn.
Clears all bindings in the scope of fn.
For example:
context.let(Key1, "value1") { context.let(Key2, "something else") { context.letClear() { // context.contains(Key1) == false // context.contains(Key2) == false } // context(Key1) == "value1" // context(Key2) == "something else" } }
Unbind the passed-in keys, in the scope of fn.
A context contains a number of let-delimited bindings. Bindings are indexed by type Key[A] in a typesafe manner. Later bindings shadow earlier ones.
Note that the implementation of context maintains all bindings in a linked list; context lookup requires a linear search.