kotovalexarian-likes-github/ruby--ruby
1
0
Fork 0
mirror of https://github.com/ruby/ruby.git synced 2022-11-09 12:17:21 -05:00
Code Releases Activity

Improve safe navigation operator's docs [Misc #15109]

Browse source 
* doc/syntax/calling_methods.rdoc: Add Safe navigation operator section.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65228 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
aycabta 2018-10-20 10:57:33 +00:00
parent 4d4b60acea
commit ecc627b20a
1 changed files with 23 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
doc/syntax/calling_methods.rdoc
View file

@ -27,13 +27,32 @@ This sends the +my_method+ message to +my_object+. Any object can be a
receiver but depending on the method's visibility sending a message may raise a
NoMethodError.
You may use <code>&.</code> to designate a receiver, then +my_method+ is not
invoked and the result is +nil+ when the receiver is +nil+. In that case, the
arguments of +my_method+ are not evaluated.
You may also use <code>::</code> to designate a receiver, but this is rarely
used due to the potential for confusion with <code>::</code> for namespaces.
=== Safe navigation operator
<code>&.</code>, called "safe navigation operator", allows to skip method call
when receiver is +nil+. It returns +nil+ and doesn't evaluate method's arguments
if the call is skipped.
REGEX = /(ruby) is (\w+)/i
"Ruby is awesome!".match(REGEX).values_at(1, 2)
# => ["Ruby", "awesome"]
"Python is fascinating!".match(REGEX).values_at(1, 2)
# NoMethodError: undefined method `values_at' for nil:NilClass
"Python is fascinating!".match(REGEX)&.values_at(1, 2)
# => nil
This allows to easily chain methods which could return empty value. Note that
<code>&.</code> skips only one next call, so for a longer chain it is necessary
to add operator on each level:
"Python is fascinating!".match(REGEX)&.values_at(1, 2).join(' - ')
# NoMethodError: undefined method `join' for nil:NilClass
"Python is fascinating!".match(REGEX)&.values_at(1, 2)&.join(' - ')
# => nil
== Arguments
There are three types of arguments when sending a message, the positional