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<title>4.4.3 Differ Objects
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<H2><A NAME=
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"differ-objects"></A>
Note that
<tt class=
"class">Differ
</tt>-generated deltas make no claim to be
<strong>minimal
</strong> 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
<tt class=
"class">Differ
</tt> class has this constructor:
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><span class=
"typelabel">class
</span> <tt id='l2h-
947' xml:id='l2h-
947'
class=
"class">Differ
</tt></b>(
</nobr></td>
<td><var></var><big>[
</big><var>linejunk
</var><big>[
</big><var>, charjunk
</var><big>]
</big><var></var><big>]
</big><var></var>)
</td></tr></table></dt>
Optional keyword parameters
<var>linejunk
</var> and
<var>charjunk
</var> are
for filter functions (or
<code>None
</code>):
<var>linejunk
</var>: A function that accepts a single string
argument, and returns true if the string is junk. The default is
<code>None
</code>, meaning that no line is considered junk.
<var>charjunk
</var>: A function that accepts a single character argument
(a string of length
1), and returns true if the character is junk.
The default is
<code>None
</code>, meaning that no character is
<tt class=
"class">Differ
</tt> objects are used (deltas generated) via a single
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
948' xml:id='l2h-
948'
class=
"method">compare
</tt></b>(
</nobr></td>
<td><var>a, b
</var>)
</td></tr></table></dt>
Compare two sequences of lines, and generate the delta (a sequence
Each sequence must contain individual single-line strings ending
with newlines. Such sequences can be obtained from the
<tt class=
"method">readlines()
</tt> method of file-like objects. The delta generated
also consists of newline-terminated strings, ready to be printed as-is
via the
<tt class=
"method">writelines()
</tt> method of a file-like object.
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<span class=
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2.4.2, documentation updated on
28 September
2005.
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