SYNOPSIS

ns_adp_abort ?result?
ns_adp_break ?result?
ns_adp_exception ?varName?
ns_adp_return ?result?

DESCRIPTION

These commands enable early return and interrupt of an ADP execution. Internally, the exception routines sets a flag and return TCL_ERROR to begin unwinding the current Tcl call stack and return control to the ADP evaluation engine. It is possible for an enclosing catch command to catch the exception and stop Tcl from returning control to ADP. The ns_adp_exception command can be used to test for this condition.

ns_adp_abort ?result?

This command stops ADP processing, raising an execution and unwinding the stack to the top level as an error condition. The request handling code which invokes the first ADP file will normallly generate an error message in this case, ignoring the contents of the output buffer, if any. Note that the exeception can be caught by a catch command in script block which executes ns_adp_abort. However, when that block returns control to the ADP execution engine, the stack will be continue to be unwound. The optional result argument, if present, will be used to set the Tcl interpreter result string.

ns_adp_break ?result?

This command stops execution of ADP and unwinds the ADP call stack. Unlike ns_adp_abort, the request handling code will generate a normal HTTP response with any contents of the output buffer. The optional result argument, if present, will be used to set the Tcl interpreter result string.

ns_adp_exception ?varName?

This command returns a boolean value if an exception has been raised. The optional varName provides the name of a variable to store one of ok, break, abort, or return to indicate the type of exception raised.

ns_adp_return ?result?

This function halts processing of the current ADP and sends any pending output (from ns_adp_puts or static HTML) up to the point where it was called to the browser. Nothing in the current ADP is output or executed after it is called. The return_value, if specified, becomes the return value of the ADP. Note that this function returns only one level up the call stack. By contrast, ns_adp_abort and ns_adp_break will return all the way up the call stack. ns_adp_return is typically used from an ADP included by another ADP, to stop processing of the inner ADP while allowing the calling ADP to continue. The optional result argument, if present, will be used to set the Tcl interpreter result string.

EXAMPLE

The following example demonstrates halting execution of the ADP after returning a complete response with one of the ns_return style commands:

<%
if !$authorized {
   ns_returnunauthorized; # Send complete response.
   ns_adp_abort; # Execution stops here.
}
%>.

KEYWORDS

ADP, dynamic pages, exception