[SOLVED] Is assignment in a conditional clause good ruby style?

Is assignment in a conditional clause good ruby style?

In order to write more concisely, rather than do this:

test_value = method_call_that_might_return_nil()
if test_value
  do_something_with test_value
end

I've been assigning in the conditional:

if test_value = method_call_that_might_return_nil()
  do_something_with test_value
end

Is this bad style? The still-more-concise syntax:

do_something_with test_value if test_value = method_call_that_might_return_nil()

is not allowed, as discussed in another SO question, and will remain that way in 1.9, according to Matz (http://redmine.ruby-lang.org/issues/show/1141).

Given the possible confusion of assignment and comparison, does this make it too hard to read the code?

Solution

It is GOOD style to use assignments in conditionals. If you do so, wrap the condition in parentheses.

# bad (+ a warning)
if v = array.grep(/foo/)
  do_something(v)
  # some code
end

# good (MRI would still complain, but RuboCop won't)
if (v = array.grep(/foo/))
  do_something(v)
  # some code
end

# good
v = array.grep(/foo/)
if v
  do_something(v)
  # some code
end

See the community style guide for more information