And Begin Idiom to avoid if with assignments

and_begin_idiom.rb

# After reading this comment
# http://avdi.org/devblog/2010/08/02/using-and-and-or-in-ruby/#comment-1098 ,
#
# I became aware of a cool idiom for Ruby.
#
# I've seen this in a lot of cases:

if (variable = expression_or_method(options))
  variable.calculate_something
  do_other_stuff(variable)
end

# This is another way to code the same concept:

variable = expression_or_method(options) and begin
  variable.calculate_something
  do_other_stuff(variable)
end

# The former case issues a warning because we're using = in an if statement.
# The latter seems more semantic to me too.
# What do you think??? Comments below!

Heavily dislike the 2nd syntax. It's extremely clever and hard to read. You should be asking yourself: Will the next person to read this code have a clear idea what I've done? I can't see yes being the answer.

Thinking in that way I agree with @evanphx. Second syntax is not common and most of people we don't know how it works.

i prefer the if, by far.

In the second, there seems to be a condition

Typically, when I'm doing something like this, I want to be able to specify an elsif or else condition, which isn't possible using begin, for instance:

if rubygem = Rubygem.find_by_name(gem_name)
  render :json => rubygem.public_versions
else
  render :text => "This rubygem could not be found.", :status => 404
end