Is it possible to dynamically set variables in ruby?

Question

I am wondering if it is possible, given that these global variables exist and are accessed by other functions, to tell a function to use one variable or another without re-writing huge chunks of code. I have to use global variables because of my limitations with calabash passing variables around (correct me if I'm wrong). I want to be able to call one function that can grab information and stuff it into one of several global variables. Something hopefully like this:

def add_five(my_var)

   if my_var == "my_cats"
      use $my_cats for my_var_nickname
   elsif my_var == "my_dogs"
      use $my_dogs for my_var_nickname
   elsif my_var == "my_birds"
      use $my_birds for my_var_nickname
   end

   my_var_nickname = my_var_nickname + 5
end

$my_cats = 2
$my_dogs = 3
$my_birds = 3

add_five("my_cats")

$my_cats = 7
$my_dogs = 3
$my_birds = 3

Thanks for the help!

You could write something like b = ((stuffy == "foo") ? $A : $B) and then use b, but you should try to avoid using global variables. — Cary Swoveland
– Cary Swoveland, Commented Oct 22, 2014 at 19:42
I unfortunately don't have much choice when using calabash. I need a way to record and communicate data back and forth between test steps. — Metomorphose
– Metomorphose, Commented Oct 22, 2014 at 20:21

Raffael · Accepted Answer · 2014-10-23 00:37:09Z

1

I second the point that using global variables has a foul smell to it...

Anyway, you could try using a hash:

$animal_counts = {}
def add_five(animal_type)
  $animal_counts[animal_type] += 5
end

$animal_counts[:cats]  = 2
$animal_counts[:dogs]  = 3
$animal_counts[:birds] = 3

add_five(:cats)

$animal_counts[:cats]  # => 7
$animal_counts[:dogs]  # => 3
$animal_counts[:birds] # => 3

Hope that helps!

answered Oct 23, 2014 at 0:37

Raffael

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1 Comment

Metomorphose Over a year ago

Hmm that is interesting. In my actual case, the globals are already hashes themselves... I'll have to look into this one more.

Brennan · Accepted Answer · 2014-10-22 19:34:22Z

0

def record_as(stuff)
   variable_to_use = if stuff == "foo"
      $variableA
   elsif stuff == "bar"
      $variableB
   end

   #do stuff with variable_to_use
end

answered Oct 22, 2014 at 19:34

Brennan

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5 Comments

Metomorphose Over a year ago

Will that save it back in the original variable or is that just making a copy of it to use in that function?

Brennan Over a year ago

This creates a new reference to the variable, so editing the new reference will reflect on the global

gunr2171 Over a year ago

While this code snippet may solve the question, including an explanation really helps to improve the quality of your post. Remember that you are answering the questions for readers in the future, and those people might not know the reasons for your code suggestion.

Metomorphose Over a year ago

I tried it, and the information never made it back out to the global variable. It could have something to do with the fact that it's in the middle of a calabash step too though.

the Tin Man Over a year ago

We don't use variableA for variable names in Ruby by convention, whether they're global or not. Instead, use snake_case, variable_a.

Chathura Palihakkara · Accepted Answer · 2014-10-24 04:22:11Z

For simple use In your ruby step file define a variable like this

$global_memory=""

In your calabash step which is ok to be in another ruby step file. Read some text from query and store it on that variable in run time.

Then I should memorize delivery time

Which define in ruby step file like this

Then /^I should memorize delivery time$/ do
  srctext=query("label marked:'lblOrderTime'",:text).first
  srctext=srctext.to_s
  $global_memory.replace(srctext)
end

Later in the scenario you can recall that value and use it like this

Then I should see order dispatch time same as in checkout screen and receipt screen

Which define in ruby step file like this

Then /^I should see order dispatch time same as in checkout screen and receipt screen$/ do |arg|
  datetext=$global_memory
    result = query("webView css:'SPAN' index:5").first["textContent"].include? "#{datetext}"
    unless result
      textFound = query("webView css:'TABLE' index:0").first["textContent"]
      screenshot_and_raise "time  #{datetext} not found instead #{textFound} is found"
    end 
end

Further you can use Hash (Key value pairs) to store many variable at same time and retrieve them.

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