(guile.info.gz) Exceptions
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26.7 Exceptions
===============
A common requirement in applications is to want to jump "non-locally"
from the depths of a computation back to, say, the application's main
processing loop. Usually, the place that is the target of the jump is
somewhere in the calling stack of procedures that called the procedure
that wants to jump back. For example, typical logic for a key press
driven application might look something like this:
main-loop:
read the next key press and call dispatch-key
dispatch-key:
lookup the key in a keymap and call an appropriate procedure,
say find-file
find-file:
interactively read the required file name, then call
find-specified-file
find-specified-file:
check whether file exists; if not, jump back to main-loop
...
The jump back to `main-loop' could be achieved by returning through
the stack one procedure at a time, using the return value of each
procedure to indicate the error condition, but Guile (like most modern
programming languages) provides an additional mechanism called
"exception handling" that can be used to implement such jumps much more
conveniently.
Menu
* Exception Terminology Different ways to say the same thing.
* Catch Setting up to catch exceptions.
* Throw Throwing an exception.
* Lazy Catch Catch without unwinding the stack.
* Exception Implementation How Guile implements exceptions.
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