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Other Flavored Commands

This chapter describes Emacs commands to a Lisp process that are specific to various flavors of Lisp. They are of two varieties. Those commands that are strictly unique to a specific Lisp type and those that are common to all Lisp types but have some differences. Most of the second variety are differences in the effect of prefix arguments to common commands. These differences are specified in this document as an extension to the vanilla command using notation form "Lisp Type Specific Actions:" instead of the "Actions:" forms which are used in the vanilla commands section, See section Vanilla Commands.

VLS Lisp commands depend on the Lisp type specifics files, See section Type Specifics Files. If a specific Lisp type does not provide a way to provide the full semantics of a vanilla command then a command specifics parameter might be missing for that Lisp type. For example some Lisps do not have multiprocessing capabilities so the multiprocessing VLS commands would not work. When executing such a command an error message will be issued saying that it did not find a command string for the parameter. The missing parameter command string may be due the author of the Lisp specifics files not knowing how or not get to defining that parameter. The user is encouraged to try and define such a parameter.

Allegro Flavored Commands

Command: vls-back-trace Lisp Type Specific Actions: A positive numeric prefix argument N prints the N stack frames around the current stack frame. With a C-u prefix argument prints all significant stack frames. With a 0 numeric prefix argument prints all stack frames.

Clisp Flavored Commands

Command: vls-back-trace Lisp Type Specific Actions: A positive numeric prefix argument N between 1 and 5 sets mode to mode-N then back trace. The mode holds for all following vls-back-trace without prefix arguments. Initially the mode is mode-4 so a prefix argument of 4 will put you back to the initial mode. A C-u prefix argument prints maximum stack frames (same as mode-1) and a 0 prefix argument prints just the apply stack frames (same as mode-5).

Command: vls-return-frame Lisp Type Specific Actions: Clisp overrides the vanilla semantics of vls-return-frame such that instead of with a C-u prefix argument prompting the user for a new value and nil otherwise, always prompts the user for a return/continue value in the current Lisp buffer.

CMU CL Flavored Commands

Command: vls-back-trace Lisp Type Specific Actions: A positive prefix argument N prints N stack frames down from the current stack frame and including the current.

GCL Flavored Commands

Command: vls-back-trace Lisp Type Specific Actions: A positive numeric prefix argument N prints N stack frames from top of stack. A C-u prefix argument prints a short version of the stack frames.

LispWorks Flavored Commands

Command: vls-back-trace Lisp Type Specific Actions: A positive numeric prefix argument N prints N stack frames down from current stack frame. A 0 prefix argument print all objects found in the current stack frame. A C-u prefix argument prints a very detailed version of all stack frames.

MIT Scheme Flavored Commands

Command: vls-return-frame Lisp Type Specific Actions: MIT Scheme overrides the vanilla semantics of vls-return-frame such that instead of with a C-u prefix argument prompting the user for a new value and nil otherwise, always prompts the user for a return/continue value in the current Lisp buffer.

Scheme Flavored Commands

This section applies to all Scheme types.

Command: vls-help Lisp Type Specific Actions: Scheme implementations tend to not put the user into a debugger when an error or exception is encountered. Instead the user is expected to change this behavior or explicitly put himself in the debugger with a call to debug. To simulate the vanilla behavior the packaged VLS Lisp type specifics files debugging commands automatically put the user into the debugger, do the action indicated by the VLS command, like for example vls-back-trace, and then exits the debugger. Scheme Lisp types override the vanilla command for vls-help to work differently from these kinds of VLS debugging commands. It puts the user in the debugger and prints the help list but does not exit the debugger. The rationale here is that if the user is asking for the Scheme help commands that only work in the debugger it is better to leave him there to try one.


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