eintr: Summing up zap-to-char
8.1.5 Summing up ‘zap-to-char’
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Now that we have seen how ‘search-forward’ and ‘progn’ work, we can see
how the ‘zap-to-char’ function works as a whole.
The first argument to ‘kill-region’ is the position of the cursor
when the ‘zap-to-char’ command is given—the value of point at that time.
Within the ‘progn’, the search function then moves point to just after
the zapped-to-character and ‘point’ returns the value of this location.
The ‘kill-region’ function puts together these two values of point, the
first one as the beginning of the region and the second one as the end
of the region, and removes the region.
The ‘progn’ special form is necessary because the ‘kill-region’
command takes two arguments; and it would fail if ‘search-forward’ and
‘point’ expressions were written in sequence as two additional
arguments. The ‘progn’ expression is a single argument to ‘kill-region’
and returns the one value that ‘kill-region’ needs for its second
argument.
Info Catalog
eintr: progn
eintr: zap-to-char