From: nobu@...
Date: 2014-03-07T05:12:10+00:00
Subject: [ruby-core:61348] [ruby-trunk - Feature #9602] Logic with	`Enumerable#grep`

Issue #9602 has been updated by Nobuyoshi Nakada.


Sam Rawlins wrote:
>     %w{foo bar baz}.select(/b/) {|e| e['f']}  # warns "given block not used", returns ["bar", "baz"]

It should raise a "wrong number of arguments" exception, IMO.

> ```diff
> +    for (j=0; j<RARRAY_LEN(ary); j++) {
> +	if (RTEST(rb_funcall(RARRAY_AREF(ary, j), id_eqq, 1, i))) {
> +	    rb_ary_push(memo->u2.value, i);
> ```

It should `break` after once matched.

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Feature #9602: Logic with `Enumerable#grep`
https://bugs.ruby-lang.org/issues/9602#change-45669

* Author: Tsuyoshi Sawada
* Status: Feedback
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* Category: 
* Target version: 
----------------------------------------
`Enumerable#grep` is useful to filter things:

    [nil, {}, [], 1, :foo, "foo"].grep(String)
    # => ["foo"]

1. Often, the condition cannot be expressed as a single object on which `===` is applied, but as a disjunction over `===` applied to multiple objects. I would like `Enumerable#grep` to take arbitrary number of arguments, and when they are more than one, a logical disjunction applies, just as when there are multiple comma-separated objects after `when` in `case` condition:

        [nil, {}, [], 1, :foo, "foo"].grep(String, Symbol, Array)
        # => [[], :foo, "foo"]

2. Also, it often happens that I want the negation of grep. Perhaps, `Enumerable#grepv` (`grepv` comes from `grep -v`) can be implemented as negation of `Enumerable#grep`, i.e., select elements for which `===` returns false on any of the arguments:

        [nil, {}, [], 1, :foo, "foo"].grepv(String, Symbol, Array)
        # => [nil, {}, 1]

---Files--------------------------------
select-to-accept-args.patch (2.62 KB)


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