NCL Debug Facility › Overview

Overview

The NCL Debug facility is a powerful tool to assist in the debugging of NCL procedures.

The DEBUG command has various operands which provide the NCL developer with the ability to establish a debug session. This debug session can be targeted at one or more debug scopes. A debug scope can be any of the following:

• An NCL process
• All the processes within a particular user's window
• All the processes within a particular user's logon region
• All the processes for a particular user ID (that is, all regions for that user ID)

You can have one or more debug sessions active simultaneously, each being initiated from a different environment.

A debug session is associated with a particular region that is referred to as the debugger. This region is the only region from which debug commands are accepted for the session. Any command environment can be a debugger. These environments include OCS and any &INTCMD environments.

An NCL process that falls into the scope of a debugger is associated with that debugger's environment and is referred to as a debugged NCL process. Only one debugger can debug an NCL process at a time.

After a debug session has been started, you can set break points in any procedure of any NCL process that has been attached to the debug session. The breakpoints can be set at particular points within the executed code, against the action of updating a variable, or against the execution of a nominated verb. The debugger can view or alter the data of the target NCL process. These breakpoints are external to the source and allow you to debug a process without having to modify the source code.

You can control execution of an NCL process by setting various breakpoints throughout the process. The DEBUG commands allow you to halt the execution of a process, resume execution (after a halt or breakpoint has been reached) or to step through a fixed number of process statements. You can also suspend the debug session and reestablish it at a later time. Any breakpoints or suspended processes is preserved in their current state.

The SHOW DEBUG command lets you see all your current debug sessions and their associated scopes and, optionally, the debug sessions of other users.

Note: For more information about the DEBUG and SHOW DEBUG commands, see the online help.