str_detect not implemented

[danielsjf]

str_detect('test','') 

Returns a not implemented error. More difficult to find when '' is hidden in a variable.

[hadley]

What do you expect it to do?

[danielsjf]

The same as grepl(). Return TRUE if the string is a character (or even always TRUE).

[danielsjf]

Some examples

> grepl('','hello')
[1] TRUE
> grepl('',c('hello','x'))
[1] TRUE TRUE
> grepl('',c('hello','x',5))
[1] TRUE TRUE TRUE
> grepl('',7)
[1] TRUE

The last two are more a result of implicit casting to character of the string argument.

[hadley]

It's more important for stringr to be internally consistent than to be consistent with base R functions. Currently stringr takes "" as a shortcut for boundary("character"), so I think the correct behaviour would be to return TRUE for strings that have >1 character.

[hadley]

@gagolews do you have any thoughts the correct behaviour for "detecting" boundaries?

[gagolews]

IMO an error is a fine behavior in such a case.

problematic when '' is hidden in a variable -- The error message may be confusing:

> stringr::str_detect
function (string, pattern)                                                                                                           
{                                                                                                                                    
    switch(type(pattern), empty = , bound = stop("Not implemented",                                                                                                                          
        call. = FALSE), fixed = stri_detect_fixed(string, pattern,                                                                                                                           
        opts_fixed = attr(pattern, "options")), coll = stri_detect_coll(string,                                                                                                              
        pattern, opts_collator = attr(pattern, "options")), regex = stri_detect_regex(string,                                                                                                
        pattern, opts_regex = attr(pattern, "options")))                                                                                                                                     
}

why not replacing "Not implemented" with some more informative msg?