Re: C-u C-space

[Tim X <timx@nospam.dev.null>]

A Soare <alinsoar@voila.fr> writes:

> Today I learned about this.
>
> Now I am trying to find out what command is associated with C-u C-space. I do
>
> C-h k C-u .
>
> It appears <<C-u runs the command universal-argument>> . I did not arrive to press C-space.
>
> Is it a bug? Or I used wrong describe-key ?
>

No, its not a bug. C-u is the 'universal-argument, which basically means it is
a type of modifier for some functions. So, what you need to do is look up what
C-space does and you will probably find it states that the behavior of the
function is modified by using the optional argument, which is usually refered
to as the prefix argument. See below -

Tim


,----[ C-h k  CONTROL SPACE  ]
|  CONTROL SPACE  runs the command set-mark-command
|   which is an interactive compiled Lisp function in `simple.el'.
| It is bound to  control @ ,  CONTROL SPACE .
| (set-mark-command ARG)
| 
| Set the mark where point is, or jump to the mark.
| Setting the mark also alters the region, which is the text
| between point and mark; this is the closest equivalent in
| Emacs to what some editors call the "selection".
| 
| With no prefix argument, set the mark at point, and push the
| old mark position on local mark ring.  Also push the old mark on
| global mark ring, if the previous mark was set in another buffer.
| 
| Immediately repeating this command activates `transient-mark-mode' temporarily.
| 
| With prefix argument (e.g., C-u C-@), jump to the mark, and set the mark from
| position popped off the local mark ring (this does not affect the global
| mark ring).  Use C-x C-@ to jump to a mark popped off the global
| mark ring (see `pop-global-mark').
| 
| If `set-mark-command-repeat-pop' is non-nil, repeating
| the C-@ command with no prefix argument pops the next position
| off the local (or global) mark ring and jumps there.
| 
| With C-u C-u as prefix
| argument, unconditionally set mark where point is, even if
| `set-mark-command-repeat-pop' is non-nil.
| 
| Novice Emacs Lisp programmers often try to use the mark for the wrong
| purposes.  See the documentation of `set-mark' for more information.
| 
| This function is advised.
| 
| After-advice `emacspeak':
| Produce an auditory icon if possible.
`----

-- 
tcross (at) rapttech dot com dot au