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Feature #15419

open

Allow Kernel#tap to be invoked with arguments like Kernel#send

Added by shuber (Sean Huber) over 3 years ago. Updated 5 months ago.

Status:
Open
Priority:
Normal
Assignee:
-
Target version:
-
[ruby-core:90553]

Description

Tapping methods without any arguments already has nice shorthand via Symbol#to_proc:

object.tap { |o| o.example }
# vs
object.tap(&:example)

Unfortunately once other arguments are involved we have to switch back to the longer form:

array.merge(other).tap { |a| a.delete(object) }

This patch introduces a convenient and familiar shorthand for these cases which behaves similar to Kernel#send:

array.merge(other).tap(:delete, object)

Calling tap without any arguments or block still raises LocalJumpError:

3.tap #=> LocalJumpError: no block given

This also makes the existing shorthand even shorter:

object.tap { |o| o.example }
# vs
object.tap(&:example)
# vs
object.tap(:example)

Pull request: https://github.com/ruby/ruby/pull/2050

Actions #1

Updated by shuber (Sean Huber) over 3 years ago

  • Description updated (diff)
Actions #2

Updated by shuber (Sean Huber) over 3 years ago

  • Description updated (diff)
Actions #3

Updated by shuber (Sean Huber) over 3 years ago

  • Description updated (diff)

Updated by shuber (Sean Huber) over 3 years ago

The ruby/spec on Ruby 2.3 check is failing in this PR - I'm not sure what the existing conventions are for adding specs for new features like this.

  • Should the new tests be wrapped in unless RUBY_VERSION <= "2.3" conditions?
  • Or should the new tests be added somewhere other than /spec instead?
  • Or some other convention? Please advise!

Updated by Eregon (Benoit Daloze) over 3 years ago

shuber (Sean Huber) wrote:

The ruby/spec on Ruby 2.3 check is failing in this PR - I'm not sure what the existing conventions are for adding specs for new features like this.

  • Should the new tests be wrapped in unless RUBY_VERSION <= "2.3" conditions?
  • Or should the new tests be added somewhere other than /spec instead?
  • Or some other convention? Please advise!

Yes, in such a case you need to use ruby_version_is guards as documented on https://github.com/ruby/spec/blob/master/CONTRIBUTING.md#guards,
because the behavior of previous versions will not change (unless this is decided to be backported, but very unlikely for a new feature, and even then the backport would be done later so the guards would be needed at first).

Updated by Anonymous over 3 years ago

It is not backward compatible.
And I'm not sure why we need to change just #tap and not other methods.

There are some discussions going on about passing arguments whith Symbol#to_proc shorthand: #12115, #15301, etc. Personally I'd rather see one of these implemented. It would also fix this issue.

Updated by shuber (Sean Huber) over 3 years ago

Eregon (Benoit Daloze) wrote:
Yes, in such a case you need to use ruby_version_is guards as documented on https://github.com/ruby/spec/blob/master/CONTRIBUTING.md#guards,
because the behavior of previous versions will not change (unless this is decided to be backported, but very unlikely for a new feature, and even then the backport would be done later so the guards would be needed at first).

Perfect thanks @Eregon (Benoit Daloze), pull request updated!

oleynikov (Alexander Oleynikov) wrote:
And I'm not sure why we need to change just #tap and not other methods.
There are some discussions going on about passing arguments whith Symbol#to_proc shorthand: #12115, #15301, etc. Personally I'd rather see one of these implemented. It would also fix this issue.

Thanks for the links to the other discussions @oleynikov, pretty interesting, I'll keep an eye on those as well!

For Kernel#tap specifically I think it still makes sense to allow it to accept arguments like Kernel#send since they basically behave the same aside from tap always returning self. Relying on the proposals to support Symbol#to_proc with arguments (which could take awhile until they're actually merged) looks a bit more abstract than it needs to be:

array.tap(:delete, object)
# vs
array.tap(&:delete.(object)) # if that's the syntax they agree on
# vs
array.tap { |a| a.delete(object) } # currently supported

I could get behind something like this too:

array.tap(&:delete, object)
Actions #8

Updated by hsbt (Hiroshi SHIBATA) 5 months ago

  • Project changed from 14 to Ruby master
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