Bug in ruby 1.9.2-p0 gsub?

ruby-talk
1

Why does the following only replace the first instance of the pattern?

'|\\ |\\ |'.gsub(/\|\\ \|/, "||")

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2

The pattern is matching pairs of | characters with content in between.
Once it matches the first instance, there is only a single | character
remaining in the original string. The replacement text is not taken
into consideration.

Try the following modification instead. It uses a lookahead assertion
to avoid consuming the trailing | character in each sequence:

'|\\ |\\ |'.gsub(/\|\\ (?=\|)/, "|")

Since the search does not consume the trailing | character, the
replacement string is only a single | character rather than a double.

-Jeremy

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On 11/9/2010 11:03 AM, Sd He wrote:

Why does the following only replace the first instance of the pattern?

'|\\ |\\ |'.gsub(/\|\\ \|/, "||")

3

I see. Thanks a lot, especially for the lightning response!

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