From: Space Ship Traveller <space.ship.traveller@...>
Date: 2009-09-04T12:18:31+09:00
Subject: Re: Is Passing a Binding with Parameters Possible?

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I like lmgtfy:

http://lmgtfy.com/?q=Binding+of_caller

Kind regards,
Samuel

On 4/09/2009, at 9:03 AM, John Sikora wrote:

> Does anyone know how to pass a binding using parameters instead of a
> code block? Is it even possible?
>
> For various reasons (primarily syntactic sugar implementation), I need
> to eval a string in one method in the scope of another method. The
> following is a  simplified version of the code (which works):
>
>
> def called_method(*parameters, &code_block)  # code_block handler
> ignored.
>  parameters.each do |parameter|
>    eval(parameter, code_block.binding)
>  end
> end
>
> def calling_method
>  a = 3
>  string_to_evaluate = 'puts a'
>  called_method(string_to_evaluate){}
> end
>
> calling_method       # => 3
>
>
> Obviuosly, this requires a code block for 'called_method'. In the  
> actual
> code, whenever eval is used, parameters are always present. Code  
> blocks
> are optional. So when a code block is not needed, the empty code block
> has to be included.
>
> No big deal, but it would be nice to be able to use the parameters to
> pass the binding (since they are always present when eval is used).  
> Such
> as:
>
>
> def called_method(*parameters, &code_block)  # code_block handler
> ignored.
>  parameters.each do |parameter|
>    eval(parameter, parameters.binding)
>  end
> end
>
> def calling_method
>  a = 3
>  string_to_evaluate = 'puts a'
>  called_method(string_to_evaluate)
> end
>
> calling_method      # => in 'called_method' private method 'binding'
> called...
>
>
> So I guess .binding is a private method for objects other than code
> blocks, in this case an Array. If I change 'parameters.binding' to
> 'binding', it (of course) does not give the right binding, resulting  
> in
> variable 'a' being undefined. I have tried some other code snippets  
> that
> I thought might work, but to no avail.
>
> I know a binding could be created inside of calling_method and it  
> could
> be could be passed, but the way it is now with the empty braces is
> easier, which is the point of syntactic sugar.
>
> Can it be made even easier by passing the binding 'automatically' with
> the parameters instead of a code block?
>
> John S.
> -- 
> Posted via http://www.ruby-forum.com/.
>


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