Overloading the []-Operator

ruby-talk
1

Hi,

I'm trying to overload the [ ] operator. It works fine for read-only
access:

def [](acc)
@myValues[acc]
end

However, I'd also need write access. I've tried:

def [](acc)=(value)
   @myValues[acc] = value
  end

And get a syntax error on the first line. I'd appreciate any help.

Matt

···

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Posted via http://www.ruby-forum.com/.

2

def =(acc, value)

Stefano

···

On Thursday 10 July 2008, Matthias Winkelmann wrote:

Hi,

I'm trying to overload the operator. It works fine for read-only
access:

def (acc)
@myValues[acc]
end

However, I'd also need write access. I've tried:

def (acc)=(value)
   @myValues[acc] = value
  end

And get a syntax error on the first line. I'd appreciate any help.

Matt

3

irb(main):017:0> class Junk
irb(main):018:1> def initialize ; @myValues = {} ; end
irb(main):019:1> def (acc) ; @myValues[acc] ; end
irb(main):020:1> def = (acc,value) ; @myValues[acc] = value ; end
irb(main):021:1> end
=> nil
irb(main):022:0> a = Junk.new
=> #<Junk:0xb7baa538 @myValues={}>
irb(main):023:0> a[5]
=> nil
irb(main):024:0> a[5]=5
=> 5
irb(main):025:0> a[5]
=> 5
irb(main):026:0>

···

On Thu, 2008-07-10 at 19:55 +0900, Matthias Winkelmann wrote:

Hi,

I'm trying to overload the operator. It works fine for read-only
access:

def (acc)
@myValues[acc]
end

However, I'd also need write access. I've tried:

def (acc)=(value)
   @myValues[acc] = value
  end

And get a syntax error on the first line. I'd appreciate any help.

Matt

--
Michael T. Richter <ttmrichter@gmail.com> (GoogleTalk:
ttmrichter@gmail.com)
I'm not schooled in the science of human factors, but I suspect surprise
is not an element of a robust user interface. (Chip Rosenthal)

4

Stefano Crocco wrote:

def =(acc, value)

...because the name of the method is "=", strange though that may seem
to a Ruby newbie!

···

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