| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: environment
This function returns an environment suitable for portable code walkers to use entirely within the ANSI Specification of Common Lisp.
Normally a :compiler
environment will expand
compiler-macros (though a :compilation
environment
will not do so, as per spec). The compiler does macroexpansions with
a :compiler
environment, so that the macroexpansion
process can be a part of the compilation process, and so that
compiler-savvy compiler-macros and macros can gain insights into the
compiler's inner workings. Code walkers are themselves macros or
compiler-macros at their top level (since it is only these two
entities that can get access to environments), so these
macros/compiler-macros must each make the decision as to whether they
will handle a walk portably or non-portably. A non-portable walk will
include possible compiler-macro expansions and stops at special forms
(see the documentation for the Allegro CL implementation of macroexpand and macroexpand-1 in cl:macroexpand and
cl:macroexpand in implementation.htm).
But if the walker wants to operate portably, without expansion of
compiler-macros and with macroexpansion of special forms, then this
function must be called and the result used as the environment for the
walk.
This function will always return an environment. If the
environment argument is nil
, then a new, empty
:interpreter
environment will be returned. If the
environment argument is a
:compiler
environment, then it will be augmented
once with no new information, and the result will be changed to a
:compilation
environment and returned. All other
environment arguments wil be returned unchanged.
See environments.htm for more information on environments.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |