Ruby double pipe assignment with block/proc/lambda?

Question

It is really nice to be able to write out

@foo ||= "bar_default"

or

@foo ||= myobject.bar(args)

but I have been looking to see if there is a way to write something like

@foo ||= do
  myobject.attr = new_val
  myobject.other_attr = other_new_val
  myobject.bar(args)
end

roughly equivalent in actually functional code to something like

@foo = if !@foo.nil?
         @foo
       else
         myobject.attr = new_val
         myobject.other_attr = other_new_val
         myobject.bar(args)
       end

And I suppose I could write my own global method like "getblock" to wrap and return the result of any general block, but I'm wondering if there is already a built-in way to do this.

score 44 · Accepted Answer · answered Dec 30 '12 at 04:46

44

You can use begin..end:

@foo ||= begin
  # any statements here
end

or perhaps consider factoring the contents of the block into a separate method.

answered Dec 30 '12 at 04:46

jacknagel

1,301
1
10
8

Thanks, not sure why I didn't think of this. – Misterparker Jan 03 '13 at 18:13

score 4 · Answer 2 · answered Feb 11 '15 at 21:35

4

I usually write it like this:

@foo ||= (
  myobject.attr = new_val
  myobject.other_attr = other_new_val
  myobject.bar(args)
)

answered Feb 11 '15 at 21:35

tothemario

5,851
3
44
39

For everyone who wanted to go this way, keep in mind that this style is not rubocop-compliant: `Style/MultilineMemoization: Wrap multiline memoization blocks in begin and end.` – BinaryButterfly May 09 '22 at 17:13

score -2 · Answer 3 · answered Dec 30 '12 at 04:45

-2

@foo ||= unless @foo
  myobject.attr = new_val
  myobject.other_attr = other_new_val
  myobject.bar(args)
end

answered Dec 30 '12 at 04:45

dteoh

5,794
3
27
35

Ruby double pipe assignment with block/proc/lambda?

3 Answers3