4.4.3 Differ Objects
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.
The Differ class has this constructor:
-
Optional keyword parameters linejunk and charjunk are
for filter functions (or
None
):linejunk: A function that accepts a single string argument, and returns true if the string is junk. The default is
None
, meaning that no line is considered junk.charjunk: A function that accepts a single character argument (a string of length 1), and returns true if the character is junk. The default is
None
, meaning that no character is considered junk.
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.
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