 "The listener's mechanism for reading multi-line expressions from the input stream can be called from user code:"
 { $subsections read-quot } ;
 
+HELP: handle-ctrl-break
+{ $description "If this variable is " { $link t } ", the listener will wrap the user code with calls to " { $link enable-ctrl-break } " and " { $link disable-ctrl-break } " to make it interruptible with C-Break. This includes both compilation and execution phases, so circular vocab import can be interrupted as well as infinite loops."
+$nl
+"This only works on Windows, and has no effect on other platforms."
+{ $warning "If user code " { $link yield } "s or gets stuck on an asynchronous I/O operation, pressing C-Break will most likely crash the Factor VM." } } ;
+
 ABOUT: "listener"
 
 HELP: read-quot

USING: help.markup help.syntax kernel io system prettyprint
continuations quotations vocabs parser vocabs.loader ;
IN: listener

ARTICLE: "listener-watch" "Watching variables in the listener"

{ $example "{ 1 2 3 } [\n    .\n] each" "1\n2\n3" }
"The listener will display the current contents of the datastack after every line of input."
$nl
"If your code runs too long, you can press C-Break to interrupt it (works only on Windows). To enable this feature, run the following code, or add it to your " { $link ".factor-rc" } ":"
{ $code
    "USING: listener namespaces ;"
    "t handle-ctrl-break set-global"
}
$nl
"The listener can watch dynamic variables:"
{ $subsections "listener-watch" }
"Nested listeners can be useful for testing code in other dynamic scopes. For example, when doing database maintenance using the " { $vocab-link "db.tuples" } " vocabulary, it can be useful to start a listener with a database connection:"
