role of options={}?

rubyonrails-talk
1

Hey all,

Can't find a good explanation of options={}. Specifically I'm not sure of its role in this given line of code:

helper file:

  def render_show_actions(resource, actions, options={})     commands = actions.map do |action|       send "render_show_action_#{action}", resource, options     end

controller:

  def render_show_action_pass(student, options={})     @template.link_to "pass", pass_student_path(student), :method => :get   end   helper_method :render_show_action_pass

It appears that the action in the helper dynamically builds the action in controller. But then the question is what is options doing there and which method is calling which?

Thanks for any suggestions.

2

John Merlino wrote:

Hey all,

Can't find a good explanation of options={}. Specifically I'm not sure of its role in this given line of code:

helper file:

  def render_show_actions(resource, actions, options={})     commands = actions.map do |action|       send "render_show_action_#{action}", resource, options     end

controller:

  def render_show_action_pass(student, options={})     @template.link_to "pass", pass_student_path(student), :method => :get   end   helper_method :render_show_action_pass

It appears that the action in the helper dynamically builds the action in controller. But then the question is what is options doing there and which method is calling which?

Thanks for any suggestions.

def wow array=[1]   array end

wow

copy and paste this in IRB and you'll understand. "options={}" says that if no variable is passed for 'options', make it an empty hash. The rest of the code should make some more sense.

3

if no variable is passed for 'options', make it an empty hash. The rest of the code should make some more sense.

So if no parameter is passed in, why would it need to be there?

4

It’s a default value.

In languages that don’t have default values, you always have to pass in an argument. For example, if you defined it this way (or if Ruby didn’t support them…)

def render_show_actions(resource, actions, options)

When you called the function, you’d have to do this

render_show_actions @resource, [“action 1”, "action 2] , {}

instead of this

render_show_actions @resource, [“action 1”, "action 2]

… which is much nicer looking, and less typing.

5

Aldric Giacomoni wrote:

John Merlino wrote:

Hey all,

Can't find a good explanation of options={}. Specifically I'm not sure of its role in this given line of code:

helper file:

  def render_show_actions(resource, actions, options={})     commands = actions.map do |action|       send "render_show_action_#{action}", resource, options     end

controller:

  def render_show_action_pass(student, options={})     @template.link_to "pass", pass_student_path(student), :method => :get   end   helper_method :render_show_action_pass

It appears that the action in the helper dynamically builds the action in controller. But then the question is what is options doing there and which method is calling which?

Thanks for any suggestions.

def wow array=[1]   array end

wow

copy and paste this in IRB and you'll understand. "options={}" says that if no variable is passed for 'options', make it an empty hash. The rest of the code should make some more sense.

Yup. If you're having trouble with this, please review your basic Ruby syntax.

Best,