Note that Differ-generated deltas make no claim to be
minimal diffs. To the contrary, minimal diffs are often
counter-intuitive, because they synch up anywhere possible, sometimes
accidental matches 100 pages apart. Restricting synch points to
contiguous matches preserves some notion of locality, at the
occasional cost of producing a longer diff.
Optional keyword parameters linejunk and charjunk are
for filter functions (or None):
linejunk: A function that should accept a single string
argument, and return true if the string is junk. The default is
module-level function IS_LINE_JUNK(), which filters out
lines without visible characters, except for at most one pound
character ("#").
charjunk: A function that should accept a string of length 1.
The default is module-level function IS_CHARACTER_JUNK(),
which filters out whitespace characters (a blank or tab; note: bad
idea to include newline in this!).
Differ objects are used (deltas generated) via a single
method:
Compare two sequences of lines, and generate the delta (a sequence
of lines).
Each sequence must contain individual single-line strings ending
with newlines. Such sequences can be obtained from the
readlines() method of file-like objects. The delta generated
also consists of newline-terminated strings, ready to be printed as-is
via the writelines() method of a file-like object.
