6.26.3.3 call-with-error-handling

The Guile REPL code (in system/repl/repl.scm and related files) uses a catch with a pre-unwind handler to capture the stack when an error occurs in an expression that was typed into the REPL, and debug that stack interactively in the context of the error.

These procedures are available for use by user programs, in the (system repl error-handling) module.

(use-modules (system repl error-handling))

Scheme Procedure: call-with-error-handling thunk [#:on-error on-error=’debug] [#:post-error post-error=’catch] [#:pass-keys pass-keys=’(quit)] [#:report-keys report-keys=’(stack-overflow)] [#:trap-handler trap-handler=’debug] ¶

Call a thunk in a context in which errors are handled.

Note that this function was written when throw/catch were the fundamental exception handling primitives in Guile, and so exposes some aspects of that interface (notably in the form of the procedural handlers). Guile will probably replace this function with a call-with-standard-exception-handling in the future.

There are five keyword arguments:

on-error

Specifies what to do before the stack is unwound.

Valid options are debug (the default), which will enter a debugger; pass, in which case nothing is done, and the exception is rethrown; or a procedure, which will be the pre-unwind handler.

post-error

Specifies what to do after the stack is unwound.

Valid options are catch (the default), which will silently catch errors, returning the unspecified value; report, which prints out a description of the error (via display-error), and then returns the unspecified value; or a procedure, which will be the catch handler.

trap-handler

Specifies a trap handler: what to do when a breakpoint is hit.

Valid options are debug, which will enter the debugger; pass, which does nothing; or disabled, which disables traps entirely. See Traps, for more information.

pass-keys

A set of keys to ignore, as a list.

report-keys

A set of keys to always report even if the post-error handler is catch, as a list.