Hint about [\] trick to avoid quad backslashes.
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@ -22,9 +22,10 @@ is because Python doesn't remove backslashes from string literals if
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they are followed by an unrecognized escape character.
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\emph{However}, if you want to include a literal \dfn{backslash} in a
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regular expression represented as a string literal, you have to
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\emph{quadruple} it. E.g.\ to extract \LaTeX\ \samp{\e section\{{\rm
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\emph{quadruple} it or enclose it in a singleton character class.
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E.g.\ to extract \LaTeX\ \samp{\e section\{{\rm
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\ldots}\}} headers from a document, you can use this pattern:
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\code{'\e \e \e \e section\{\e (.*\e )\}'}. \emph{Another exception:}
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\code{'[\e ] section\{\e (.*\e )\}'}. \emph{Another exception:}
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the escape sequece \samp{\e b} is significant in string literals
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(where it means the ASCII bell character) as well as in Emacs regular
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expressions (where it stands for a word boundary), so in order to
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@ -22,9 +22,10 @@ is because Python doesn't remove backslashes from string literals if
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they are followed by an unrecognized escape character.
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\emph{However}, if you want to include a literal \dfn{backslash} in a
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regular expression represented as a string literal, you have to
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\emph{quadruple} it. E.g.\ to extract \LaTeX\ \samp{\e section\{{\rm
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\emph{quadruple} it or enclose it in a singleton character class.
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E.g.\ to extract \LaTeX\ \samp{\e section\{{\rm
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\ldots}\}} headers from a document, you can use this pattern:
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\code{'\e \e \e \e section\{\e (.*\e )\}'}. \emph{Another exception:}
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\code{'[\e ] section\{\e (.*\e )\}'}. \emph{Another exception:}
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the escape sequece \samp{\e b} is significant in string literals
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(where it means the ASCII bell character) as well as in Emacs regular
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expressions (where it stands for a word boundary), so in order to
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