Assignment without attr=

Ruby
1

Not even sure what to call this for the thread subject

I want to create a class which is a simple packed set of digits (as a
string) as the one and only attribute of the class. There will be
several methods to extract chunks from and format this string, but
there’s only the one attribute.

For the life of me I can’t figure out how to to populate the dang this
to start with, without have to go through an attribute. If it were a
normal multi-attribute object, I’m fine, but in light of there only
being one attribute, I’m trying to work with it a different way. Maybe
I’m just going about it all wrong to start with?

The essentials:

class PackedNumber
def initialize
@packedNumber
end

def methodX
…
end

def methodY
…
end
end

So, I’d want to work with it like this:
whatever = PackedNumber.new(‘12345’)
Or
whatever = PackedNumber.new
whatever = ‘12345’ # but I don’t want whatever to be String

I’m trying to avoid the obvious, and maybe this is what is not possible
whatever.packedNumber = ‘12345’

I tried creating a method just for = but that didn’t fly

def =(chars)
@packedNumber = chars
end

Feels pretty lame I can’t see this, but there ya go.

– gw

2

Greg W. wrote:

being one attribute, I’m trying to work with it a different way. Maybe
…
whatever = PackedNumber.new

Feels pretty lame I can’t see this, but there ya go.

– gw

maybe I’m missing something obvious here, but why not just take the
initial value as an argument to initialize?

class PackedNumber
def initialize(packed_number)
@packedNumber = packed_number
end
# other stuff
end

pn = PackedNumber.new(‘12345’)

3

So, I’d want to work with it like this:
whatever = PackedNumber.new(‘12345’)

If that’s all you want, you can do this:

class PackedNumber
def initialize(string)
@packednumber = string
end
end

HTH,
Chris

4

Greg W. wrote:

being one attribute, I’m trying to work with it a different way. Maybe
…
end

def methodY
…
end
end

So, I’d want to work with it like this:
whatever = PackedNumber.new(‘12345’)

def initialize(num = nil)
@packedNumber = num
end

Or
whatever = PackedNumber.new
whatever = ‘12345’ # but I don’t want whatever to be String

I don’t think you can do this.

I’m trying to avoid the obvious, and maybe this is what is not possible
whatever.packedNumber = ‘12345’

I tried creating a method just for = but that didn’t fly

def =(chars)
@packedNumber = chars
end

But you could do

def set(chars)
@packedNumber = chars
end

whatever = PackedNumber.new

whatever.set ‘12345’

or if you want it even shorter, less ‘method-call-like’

def [] num
@packedNumber = num
end

whatever[‘12345’]

-Justin

5

Greg W. wrote:

  whatever = PackedNumber.new(‘12345’)
Or
  whatever = PackedNumber.new
  whatever = ‘12345’  # but I don’t want whatever to be String

Given that there is no String#~ this would work:
class String
def ~
PackedNumber.new self
end
end

whatever = ~“12345”

That a “little” hackish thogh :wink:

HTH,
Sebastian

6

Justin C. wrote:

or if you want it even shorter, less ‘method-call-like’

def [] num
@packedNumber = num
end

whatever[‘12345’]

Yeah, either of those (.set or [ ]) will be fine.

Tim H. wrote:

maybe I’m missing something obvious here, but why not just take the
initial value as an argument to initialize?

I want to allow assignment at initialization as you say, and an
alternate method too.

I’m just experimenting/exploring what’s possible.

Thanks guys.

– gw