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| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version

## boxp

Arguments: object

Returns `t` if the argument is a box object and returns `nil` otherwise.

See the description of the make-box for more information on boxes.

### Warning about positions created by the with-boxes and with-positions-and-boxes

boxp should not be called on objects created by the macros with-boxes and with-positions-and-boxes. The return value of those functions is undefined for objects created by the macros because type information for such objects is sacrificed to achieve the non-consing efficiency of stack allocation.

Copyright (c) 1998-2019, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.2 page.
Created 2012.5.30.

|  | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version