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void | seed_make_exception () |
gchar * | seed_exception_get_name () |
gchar * | seed_exception_get_message () |
guint | seed_exception_get_line () |
gchar * | seed_exception_get_file () |
gchar * | seed_exception_to_string () |
Seed uses exceptions as a method of handling runtime errors within scripts. An exception consists of a name (a list of commonly-used exception names is below), a message, detailing the error, and the line number and filename from which the exception was raised. If Seed cannot determine from where the exception was raised, the line number and filename will be undefined. seed_exception_to_string()
provides a simple way to convert all of these into a consistent representation to display to users.
All Seed callbacks take an exception argument; calling
seed_make_exception()
with this argument and the details you wish to
fill it with will propogate that exception up the chain. Exceptions
can be caught either by a try/catch block in the
calling JavaScript, or by observing the exception property, dealing
with it, and then clearing the exception.
It is important to note that calling seed_make_exception()
does not
in fact throw the exception, but just creates an
object which, when stored in the exception pointer passed to a callback,
causes JSC to throw an exception once flow is returned.
Example 9. Throw an exception, because random_callback
was called with the wrong number of arguments
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 |
SeedValue random_callback(SeedContext ctx, SeedObject function, SeedObject this_object, gsize argument_count, const SeedValue arguments[], SeedException *exception) { ... if(argument_count != 1) { seed_make_exception(ctx, exception, "ArgumentError", "wrong number of arguments; expected 1, got %zd", argument_count); return seed_make_undefined(ctx); } ... } |
void seed_make_exception (SeedContext ctx
,SeedException exception
,const gchar *name
,const gchar *message
,...
);
Creates a new JavaScript exception with the given attributes.
The line number and file name of the exception created will be undefined.
ctx |
A SeedContext. |
|
exception |
A reference to a SeedException in which to store the exception. |
|
name |
The gchar* representing the exception name. |
|
message |
The gchar*, as a printf format string, representing the details of the exception. |
gchar * seed_exception_get_name (SeedContext ctx
,SeedException exception
);
Retrieves the name of the given exception; this could be one of the predefined exception names given above, or your own name, which should be a single CamelCase word, preferably ending in something like "Error".
gchar * seed_exception_get_message (SeedContext ctx
,SeedException exception
);
Retrieves the message of the given exception; this should be a human-readable string describing the exception enough that a developer could utilize the message in order to determine where to look to debug the problem.
guint seed_exception_get_line (SeedContext ctx
,SeedException exception
);
Retrieves the line number the given exception was thrown from; keep in mind that exceptions created from C have an undefined line number.
gchar * seed_exception_get_file (SeedContext ctx
,SeedException exception
);
Retrieves the file name the given exception was thrown from; keep in mind that exceptions created from C have an undefined file name.
gchar * seed_exception_to_string (SeedContext ctx
,SeedException exception
);
Properly formats the name, detailed message, line number, and file name of the given extension. This provides a consistent format for printed exceptions, to reduce confusion. Please use it if you're exposing exception data to the outside world.