String#-@

() -> self

-string → frozen_string

static VALUE
str_uminus(VALUE str)
{
    if (!BARE_STRING_P(str) && !rb_obj_frozen_p(str)) {
        str = rb_str_dup(str);
    }
    return rb_fstring(str);
}

Returns a frozen, possibly pre-existing copy of the string.

The returned String will be deduplicated as long as it does not have any instance variables set on it and is not a String subclass.

Note that -string variant is more convenient for defining constants:

Example

FILENAME = -'config/database.yml'

while dedup is better suitable for using the method in chains of calculations:

Example

@url_list.concat(urls.map(&:dedup))

Ruby version changes

3.2
- String#dedup has been added as an alias to String#-@. [Feature #18595]

See also #+@ #<< #+ #<=> also in 4.1 · 4.0 · 3.3 · 3.2 · 3.1 · 3.0

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