library(knitr)
opat = knit_patterns$get() # old pattern list (to restore later)
apats = all_patterns # a list of all built-in patterns
str(apats)
knit_patterns$set(apats[["rnw"]]) # set pattern list from apats
knit_patterns$get(c("chunk.begin", "chunk.end", "inline.code"))
# a customized pattern list; has to empty the original patterns first!
knit_patterns$restore()
# we may want to use this in an HTML document
knit_patterns$set(list(chunk.begin = "<!--helloR\\s+(.*)", chunk.end = "^byeR-->"))
str(knit_patterns$get())
knit_patterns$set(opat) # put the old patterns back
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