Feature #10017: Add `Hash#fetch_values`

• Status: Closed
• Assignee: matz (Yukihiro Matsumoto)
• Target version: -

[wojtekmach (Wojtek Mach)]

I'm proposing to add a new method Hash#values_at! that's basically a combination of #values_at and #fetch.

When dealing with configuration I prefer to use #fetch to fail early and this would be useful to read multiple keys at a time.
An example (not strictly on a Hash, but you get the idea) could be:

repo, token = ENV.values_at!('GITHUB_REPO', 'GITHUB_TOKEN')

ENV.values_at!('INVALID') # raises KeyError

# not sure if that useful, but I provide it here for the sake of completeness
ENV.values_at!("SHELL", "INVALID") { |k| k + " is missing" } # => ["/bin/bash", "INVALID is missing"]

Another name for this could be #fetch_at, perhaps.

P.S. I'm attaching a patch that was done using mostly trial and error

[shyouhei (Shyouhei Urabe)]

fetch_at sounds much better than values_at! to me.

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)

+1 for fetch_at.

[wojtekmach (Wojtek Mach)]

• File fetch_at.patch fetch_at.patch added

I attached another patch calling this method fetch_at and I also added missing tests (I couldn't change issue title & body to reflect this changes, though).

Also, perhaps out of scope for this ticket but I'm wondering what're your thoughts about adding #fetch_at to ENV and Array too.

[avit (Andrew Vit)]

Please consider the name fetch_at carefully: it seems easily confused with fetch (1 key), and the name doesn't hint that it's for multiple keys. (values_at is plural, so it gives a good clue.) Maybe fetch_values?

[wojtekmach (Wojtek Mach)]

Andrew Vit wrote:

Please consider the name fetch_at carefully: it seems easily confused with fetch (1 key), and the name doesn't hint that it's for multiple keys. (values_at is plural, so it gives a good clue.) Maybe fetch_values?

Personally, I prefer fetch_at but fetch_values (or fetch_values_at) is also good!

I'm curious what other core developers think.

[matz (Yukihiro Matsumoto)]

For the reason Andrew pointed out, I also prefer #fetch_values.
Maybe we need to conduct voting?

Matz.

[jihwans (Jihwan Song)]

one vote for #values_at

[phluid61 (Matthew Kerwin)]

-1 for values_at! (this isn't a "!" method)

+0 for fetch_at (it's not clear that it isn't just an alias for #fetch)

+1 for fetch_values

[wojtekmach (Wojtek Mach)]

Should we get some more votes here, or should I just change my patch to use fetch_values?

[wojtekmach (Wojtek Mach)]

I submitted PR for this change: https://github.com/ruby/ruby/pull/776 calling the method fetch_values.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Assigned
• Assignee set to matz (Yukihiro Matsumoto)

Matz, can we introduce this Hash#fetch_values?

[wojtekmach (Wojtek Mach)]

• Subject changed from Add `Hash#values_at!` to Add `Hash#fetch_values!`

Hi, please let me know if there's anything I can do to move this ticket forward.

[wojtekmach (Wojtek Mach)]

• Subject changed from Add `Hash#fetch_values!` to Add `Hash#fetch_values`

[matz (Yukihiro Matsumoto)]

#fetch_values approved.

Matz.

[nobu (Nobuyoshi Nakada)]

• Status changed from Assigned to Closed

Applied in changeset r50845.

---

hash.c: fetch_values

• hash.c (rb_hash_fetch_values): add Hash#fetch_values.
  [Feature #10017] [Fix GH-776]

[mame (Yusuke Endoh)]

• Related to Feature #20702: Add `Array#fetch_values` added