Feature #15822: Add Hash#except

• Status: Open
• Priority: Normal
• Assignee: -
• Target version: -

[timoschilling (Timo Schilling)]

According to Hash#slice, I would like to add Hash#except. Same for ENV.except.

[nobu (Nobuyoshi Nakada)]

• Is duplicate of Feature #8499: Importing Hash#slice, Hash#slice!, Hash#except, and Hash#except! from ActiveSupport added

[timoschilling (Timo Schilling)]

• File deleted (hash-except.patch)

[timoschilling (Timo Schilling)]

• File hash-except.patch hash-except.patch added

[matz (Yukihiro Matsumoto)]

• Related to Feature #13563: Implement Hash#choice method. added

[matz (Yukihiro Matsumoto)]

Hash#slice was introduced via discussion in #13563. We didn't see the need for Hash#except yet. Any (real world use-case)?
I don't think the name except is the best name for the behavior.

Matz.

[zverok (Victor Shepelev)]

matz (Yukihiro Matsumoto) About use-cases, there are multiple, like:

• Logging/debug printing some hash with sensitive or too large data excluded:

  puts "REQUEST: #{request_data.except(:body, :apikey)}

• Data tidying:

  CSV.read('data.csv', headers: true).map(&:to_h).map { |row| OpenStruct.new(row.except("Manager comment")) }

• Data conversion:

  paragraphs.map { |para| ParaStats.new(para.to_h.except(:text)) }

...and so on (without even mentioning working with models in Rails, where it is used extensively to, for example, copy model without its id and timestamps).
Redmine's sources, for example, make some use of it:

$ grep -F ".except(" {app,lib} -r | wc -l
27

I recently stumbled upon it, too.

About the name: I understand "ActiveSupport uses this name" is kinda lazy one, but it does :) And, TBH, for me (even before I started working with Rails, I used Ruby for first my 12 years without ActiveSupport) it always felt natural: request.except(:path, :body) requires no further explanations. Facets uses the name, too.

The alternative method name I can think of is, maybe, descriptive without_keys(*keys) (or except_keys, or just without(*keys)), but I am not sure it is any better.