Initial revision

1 files changed, 111 insertions, 0 deletions

diff --git a/Python/errors.c b/Python/errors.c
new file mode 100644
index 0000000..ac34742
--- /dev/null
+++ b/Python/errors.c
@@ -0,0 +1,111 @@
+/* Error handling -- see also run.c */
+
+/* New error handling interface.
+
+   The following problem exists (existed): methods of built-in modules
+   are called with 'self' and 'args' arguments, but without a context
+   argument, so they have no way to raise a specific exception.
+   The same is true for the object implementations: no context argument.
+   The old convention was to set 'errno' and to return NULL.
+   The caller (usually call_function() in eval.c) detects the NULL
+   return value and then calls puterrno(ctx) to turn the errno value
+   into a true exception.  Problems with this approach are:
+   - it used standard errno values to indicate Python-specific errors,
+     but this means that when such an error code is reported by UNIX the
+     user gets a confusing message
+   - errno is a global variable, which makes extensions to a multi-
+     threading environment difficult; e.g., in IRIX, multi-threaded
+     programs must use the function getoserror() (sp.?) instead of
+     looking in errno
+   - there is no portable way to add new error numbers for specic
+     situations -- the value space for errno is reserved to the OS, yet
+     the way to turn module-specific errors into a module-specific
+     exception requires module-specific values for errno
+   - there is no way to add a more situation-specific message to an
+     error.
+  
+  The new interface solves all these problems.  To return an error, a
+  built-in function calls err_set(exception), err_set(valexception,
+  value) or err_setstr(exception, string), and returns NULL.  These
+  functions save the value for later use by puterrno().  To adapt this
+  scheme to a multi-threaded environment, only the implementation of
+  err_setval() has to be changed.
+*/
+
+#include <stdio.h>
+
+#include "PROTO.h"
+#include "object.h"
+#include "stringobject.h"
+#include "errors.h"
+
+/* Last exception stored by err_setval() */
+
+static object *last_exception;
+static object *last_exc_val;
+
+void
+err_setval(exception, value)
+	object *exception;
+	object *value;
+{
+	if (last_exception != NULL)
+		DECREF(last_exception);
+	if (exception != NULL)
+		INCREF(exception);
+	last_exception = exception;
+	
+	if (last_exc_val != NULL)
+		DECREF(last_exc_val);
+	if (value != NULL)
+		INCREF(value);
+	last_exc_val = value;
+}
+
+void
+err_set(exception)
+	object *exception;
+{
+	err_setval(exception, (object *)NULL);
+}
+
+void
+err_setstr(exception, string)
+	object *exception;
+	char *string;
+{
+	object *value = newstringobject(string);
+	err_setval(exception, value);
+	if (value != NULL)
+		DECREF(value);
+}
+
+int
+err_occurred()
+{
+	return last_exception != NULL;
+}
+
+void
+err_get(p_exc, p_val)
+	object **p_exc;
+	object **p_val;
+{
+	*p_exc = last_exception;
+	last_exception = NULL;
+	*p_val = last_exc_val;
+	last_exc_val = NULL;
+}
+
+void
+err_clear()
+{
+	if (last_exception != NULL) {
+		DECREF(last_exception);
+		last_exception = NULL;
+	}
+	if (last_exc_val != NULL) {
+		DECREF(last_exc_val);
+		last_exc_val = NULL;
+	}
+}