generate-interrupt-checks-switch

As with all compiler switch variables, the value of this variable can be t, nil, or a function object that accepts five arguments and returns t or nil. The arguments passed to the function will be the values of the safety, space, speed, debug, and compilation-speed optimization qualities, in that order. nil is equivalent to a function that always returns nil and t to a function that always returns t. When the value is a function and we say t (or true) or nil (or false) in the text below, we mean that the function returns, respectively, t or nil.

If true, code that checks for an interrupt (Control-C on Unix, Break/Pause on Windows) is added in two places in compiled code: (1) at the beginning of the code vector and (2) at any place there is the equivalent of a cl:go in a tagbody (one such place is at least once in an iterative constructs like loops). The initial value is false (meaning that interrupt checking code is not added) only if speed is 3 and safety is 0.

Note that a loop that does not call functions will not be interruptable (either by user action or process/thread preemptions) though users can interrupt by multiple Control-C's (Unix) or using the Franz icon on the system tray (Windows). See startup.htm for more information on interrupting when all else fails.

See compiling.htm for information on the compiler.

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This page has had significant revisions compared to the 8.1 page.
Created 2016.6.21.