From: "Sebastjan H." <lists@...>
Date: 2012-08-26T22:12:24+09:00
Subject: Re: learning by doing part 2 - tc game

Jan E. wrote in post #1073054:
> Hi,
>
> The "defined?" operator is simply wrong in this case. It checks *the
> current scope* for variables, methods etc.
>
> For example:
>
> x = 0
> C = 15
> puts defined? x  # this outputs "local-variable"
> puts defined? C  # this outputs "constant"
> puts defined? a  # this outputs nothing (because the result is nil)
>
> You want something completely different, namely check if an object has a
> specific method. That's what Object#respond_to? is for:
>
> def effect_output(card)
>   if card.respond_to? :attack
>     puts "#{card.name.capitalize} hits with #{card.attack}."
>   elsif card.respond_to? :heal
>     puts "#{card.name.capitalize} heals for #{card.heal}."
>   end
> end
>
> This will call "attack" and "heal" only if the card object does actually
> have those methods.
>
> What should have made you suspicious is that you never had to specify
> any object. How is Ruby then supposed to know that you want to look into
> the card object?
>
> By the way, the reason why your program output something after you used
> a symbol is that
>
> defined? :attack
>
> returns "expression" (which is truthy).

Thank you. That helped. I actually was wondering why I didn't have to 
specify an object, but I just couldn't make the connection.

Anyway, I think I am finished with the game for now. It runs ok and I've 
also included a couple of different arenas which influence on the 
possibility of critical strikes. It's fun to play regarding it's my 
first game and it runs in the command line:)

I also rewrote all the parts where I misused the instance variables.

kind regards,
seba

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