Ruby reflection - get method definition as a string

Ruby
1

Hi Folks - I am running some ruby tests and would like to print out
the actual test to the console or store it to a file. The tests are
written as classes with a setup, run, and teardown method.
So here’s my question: is there a way to get the class definition or
method definitions as a “string”, so that I can print it out (to a
file or console)?
I know ruby supports a lot of reflection (like .methods
or .constants), but I’m not seeing how to do this.
Thanks!

2

Hi Folks - I am running some ruby tests and would like to print out
the actual test to the console or store it to a file. The tests are
written as classes with a setup, run, and teardown method.
So here’s my question: is there a way to get the class definition or
method definitions as a “string”, so that I can print it out (to a
file or console)?
I know ruby supports a lot of reflection (like .methods
or .constants), but I’m not seeing how to do this.

A very non-elegant, trivial way using Ruby’s DATA stream :wink: :

test.rb

def foo
puts “hi”
end

flag = nil
DATA.tap{|x| x.rewind}.readlines.each do |line|
flag = true if line =~ /^def/
puts line if flag
flag = false if line =~ /^end/
end
END

$ ruby test.rb
def foo
puts “hi”
end

Obviously you will have to come up with better heuristics to determine
the end of a method.

3

On Feb 17, 2011, at 8:40 PM, Anurag P. wrote:

end
END

$ ruby test.rb
def foo
puts “hi”
end

Obviously you will have to come up with better heuristics to determine
the end of a method.

In Ruby 1.9, you can retrieve the place where the method was defined
using #source_location:

def foo

end

method(:foo).source_location #=> [“file.rb”, 1]

The same goes for procs:

def foo(&block)
puts block.source_location.inspect
end

foo do

end #=> [“file.rb”, 5]

Regards,
Florian

4

On Thu, Feb 17, 2011 at 4:53 PM, Florian G. [email protected]
wrote:

or .constants), but I’m not seeing how to do this.
flag = true if line =~ /^def/
puts line if flag
flag = false if line =~ /^end/
end
END

Cool, I didn’t realize you access the source file using tap and rewind.

In Ruby 1.9, you can retrieve the place where the method was defined using
#source_location:
puts block.source_location.inspect
end

foo do

end #=> [“file.rb”, 5]

I just discovered #source_location a week or so ago, but I immediately
wondered if there was a way to discern the end of a block or method. I
never found one. Might one be added in a future Ruby?

5

Adam L. wrote in post #982302:

Hi Folks - I am running some ruby tests and would like to print out
the actual test to the console or store it to a file. The tests are
written as classes with a setup, run, and teardown method.
So here’s my question: is there a way to get the class definition or
method definitions as a “string”, so that I can print it out (to a
file or console)?
I know ruby supports a lot of reflection (like .methods
or .constants), but I’m not seeing how to do this.
Thanks!

I just released a gem which gives access to the source code of methods
and procs (GitHub - quix/live_ast: Live abstract syntax trees of methods and procs.). See the “to_ruby” section
of the readme. Since the string returned by to_ruby is a parsed/unparsed
version of your code, it probably won’t match the original source (and
comments will be gone), but it may suffice for your needs.

6

I haven’t looked at James’s gem, but if live_ast can map AST
structures to lines in the source, then it’d be easy to determine
which range of lines in a file is the interesting part. Then you’d
know precisely what section to grab.

~ jf

John F.
Principal Consultant, BitsBuilder
LI: http://www.linkedin.com/in/johnxf
SO: User John Feminella - Stack Overflow

On Fri, Feb 18, 2011 at 09:30, James M. Lawrence