progn
Function
progn
is a function that causes each of its arguments to be
evaluated in sequence and then returns the value of the last one. The
preceding expressions are evaluated only for the side effects they
perform. The values produced by them are discarded.
The template for a progn
expression is very simple:
(progn body...)
In zap-to-char
, the progn
expression has to do two things:
put point in exactly the right position; and return the location of
point so that kill-region
will know how far to kill to.
The first argument to the progn
is search-forward
. When
search-forward
finds the string, the function leaves point
immediately after the last character in the target string. (In this
case the target string is just one character long.) If the search is
backwards, search-forward
leaves point just before the first
character in the target. The movement of point is a side effect.
The second and last argument to progn
is the expression
(point)
. This expression returns the value of point, which in
this case will be the location to which it has been moved by
search-forward
. This value is returned by the progn
expression and is passed to kill-region
as kill-region
's
second argument.
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