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FR: resolve incompatible pattern modification earlier #60

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ctbrown opened this issue Mar 23, 2015 · 1 comment

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@ctbrown
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commented Mar 23, 2015

Please have incompatible search modifiers fixed vs perl / ignore.case be resolved at the call of these function and not defer to the str_* calls. Take the following example:

pattern <- 
  "str" %>%
  ignore.case %>%
  perl  # %>%
  # fixed -> pattern


str(pattern)
# Overriding Perl regexp matching
#  atomic [1:1] pattern
#  - attr(*, "ignore.case")= logi TRUE
#  - attr(*, "perl")= logi TRUE
#  - attr(*, "fixed")= logi TRUE

In this case, each of the match modifiers set an attribute to TRUE, though they are incompatible. If one were to examine pattern as is done in the example, the effects are unclear as they will be resolved later. A better method would have successive calls to the modifiers adjust pattern as appropriate. This can be done changing the functions. For example, fixed might become:

fixed <-   function(string) {
  if (stringr::is.perl(string)) 
    message("Overriding Perl regexp matching")
  structure(string, fixed = TRUE, perl = NULL, ignore.case = NULL )
}

Or perl = FALSE as another alternative.

@ctbrown ctbrown changed the title Feature request: resolve pattern modification functions earlier Feature request: resolve incompatible pattern modification earlier Mar 23, 2015

@ctbrown ctbrown changed the title Feature request: resolve incompatible pattern modification earlier FR: resolve incompatible pattern modification earlier Mar 23, 2015

@ctbrown

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commented Mar 30, 2015

This might not be relevant to the newer stringi based release.

@hadley hadley closed this in 15a586a Oct 30, 2015

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