in reply to Re^2: extracting dissimilar lines
in thread extracting dissimilar lines

That would fail if the second line contains more than one '='. But, if you think there's value in replacing trivial regexes (which can be dealt with by the optimizer) with complicated ones, why not:
$/ = ""; /=(\N+)\n[^=]+=\1\n/ or print while <>;
Or, as a one-liner:
perl -00ne'/=(\N+)\n[^=]+=\1\n/ or print' data-file

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Re^4: extracting dissimilar lines
by CountZero (Bishop) on Mar 26, 2012 at 22:22 UTC
    Even better!

    CountZero

    A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

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