use

Syntax

use v1=resource_provider_1 [, v2=resource_provider_2, ...]
...  # By default, 'use' is implicitly scoped to end of current block

use v1=resource_provider_1 [, v2=resource_provider_2, ...]
  ... # optional 'endUse' explicitly ends scope of 'use'.
endUse

Description

• At its core , use assigns resources to local variables within the scope of the use command.
• If an assigned variable already exists, its value is preserved and restored at the endUse command.
• The resource must implement the Use Protocol, described below.

Use Protocol

use will automatically call the following methods on a resource provider:

on_use()->SomeType

Writing use v = resource_provider becomes local v = resource_provider.on_use().

on_end_use(v:SomeType)

Returns the acquired resource to the provider.

Description

• The used resource will be correctly released if there are any returns, escapes, or exceptions thrown within the use statements.

Example

use builder = String.pool
builder.print "Hello World!"
println builder

# Equivalent to
local provider = String.pool
local builder = provider.on_use
builder.print "Hello World!"
println builder
provider.on_end_use( builder )