diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 59 |
1 files changed, 57 insertions, 2 deletions
@@ -27000,7 +27000,9 @@ and .code handle-frame are used by the .code get-frames -function to represent information about the currently established +and +.code find-frame +functions to represent information about the currently established exception catches (see the .code catch macro) and handlers @@ -27093,6 +27095,57 @@ structure may be passed as an argument to the .code invoke-catch function. +.coNP Function @ find-frame +.synb +.mets (find-frame >> [ exception-symbol <> [ frame-type ]]) +.syne +.desc +The +.code find-frame +function locates the first (innermost) instance of a specific kind of +exception frame (a catch frame or a handler frame) which is eligible +for processing an exception of a specific type. If such a frame +is found, it is returned. The returned frame object is of the same kind as the +objects which comprise the list returned by the function +.codn get-frames . +If such a frame is not found, +.code nil +is returned. + +The +.meta exception-symbol +argument specifies a match by exception type: the candidate frame +must specify in its list of matches at least one type which is an exception +supertype of +.metn exception-symbol . +If this argument is omitted, it defaults to +.code nil +which finds any handler that matches at least one type. There is no way to +search for handlers which match an empty set of types; the +.code find-frame +function skips such frames. + +The +.meta frame-type +argument specifies which frame type to find. Useful values for this +argument are the structure type names +.code catch-frame +and +.code handle-frame +or the actual structure type objects which these type names denote. +If any other value is specified, the function returns +.code nil . +If the argument is omitted, it defaults to the type of the +.code catch-frame +structure. That is to say, by default, the function looks for catch +frames. + +Thus, if +.code find-frame +is called with no arguments at all it finds the innermost catch frame, +if any exists, or else returns +.codn nil . + .coNP Function @ invoke-catch .synb .mets (invoke-catch < catch-frame < symbol << argument *) @@ -27107,7 +27160,9 @@ described by the argument, which must be a structure of type .code catch-frame returned by a call to -.codn get-frames . +.code get-frame +or +.codn find-frame . The control transfer is possible only if the catch frame represented by |