Scope::Escape Reified escape continuations
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Scope::Escape Tags

Perl module Escape escape continuations continuations reified

Scope::Escape Description

Reified escape continuations Scope::Escape is a Perl module that provides a generalized facility for non-local control transfer (jumping between stack frames), based on the well-thought-out semantics of Common Lisp. It provides operators that will capture and reify the escape (return) continuation of the current stack frame. The stack frame can then be returned from, at (nearly) any time while it still exists, via the reified continuation. This applies not only to subroutine stack frames, but also to intermediate frames for code blocks, and other kinds of stack frame. This facility can be used directly, or wrapped up to build a more structured facility.The system of reified escape continuations is fundamentally different from Perl's native eval/die exception facility. With die, the code initiating the non-local transfer has no control over where it will go to. Each eval frame gets to decide whether it wants to act as the target of the thrown exception, but it must make this decision based almost entirely on what was recorded in the exception object, because the stack frames between the die and the eval have already been unwound by that time. With reified continuations, however, the code initiating the transfer determines where it will go to (by choosing which continuation to use), and that decision can be made with all information about the circumstances still available.A reified escape continuation appears in Perl as a function object. Calling the function results in returning from the stack frame that is the target of the continuation. Values passed to the function are returned from the target stack frame. Optionally, the continuation may be blessed into the Scope::Escape::Continuation class. This class provides a method-based interface to the continuation: transferring through the continuation, and querying its state, can be performed by method calls on the continuation object. The methods can also be called directly, as functions, on unblessed continuation functions.SYNOPSIS use Scope::Escape qw(current_escape_function); $escape = current_escape_function; ... $escape->($result); use Scope::Escape::Continuation qw(current_escape_continuation); $escape = current_escape_continuation; ... $escape->go($result); Requirements: · Perl

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