Asp Forum - ruby string question

Tsunami Script

1/31/2009 6:40:00 PM

Is it possible to modify an existing ruby string without creating a new
one ?

If for example I have the following code :

x = "first string"
x = "second string"

between asigning values , the object_id() is different . Is there a
possibility to modify the first string so that after the modifications
the object_id will be the same ?

I would like to know how I could get to an empty string from "first
string". I would like to know if a clear method exists,or something
alike. I'm using ruby 1.8.7 .
--
Posted via http://www.ruby-....

7 Answers

Robert Dober

1/31/2009 6:51:00 PM

On Sat, Jan 31, 2009 at 7:40 PM, Tsunami Scripter <lyon2003@lycos.com> wrote:
> Is it possible to modify an existing ruby string without creating a new
> one ?
yes
>
> If for example I have the following code :
>
> x = "first string"
> x "second string"
x.clear << "second string"
x.sub! /first/, "second"
x[0..4] = "second"

> I would like to know how I could get to an empty string from "first
> string".
I guess my first example answers this.
HTH
Robert

--
It is change, continuing change, inevitable change, that is the
dominant factor in society today. No sensible decision can be made any
longer without taking into account not only the world as it is, but
the world as it will be ... ~ Isaac Asimov

Tsunami Script

1/31/2009 6:58:00 PM

irb(main):005:0> x = "string"
=> "string"
irb(main):006:0> x.clear
NoMethodError: undefined method `clear' for "string":String
from (irb):6
from :0

Perhaps you're using a different version of ruby .
--
Posted via http://www.ruby-....

Robert Dober

1/31/2009 7:20:00 PM

On Sat, Jan 31, 2009 at 7:57 PM, Tsunami Scripter <lyon2003@lycos.com> wrote:
> irb(main):005:0> x = "string"
> => "string"
> irb(main):006:0> x.clear
> NoMethodError: undefined method `clear' for "string":String
> from (irb):6
> from :0
>
> Perhaps you're using a different version of ruby .
Yup, I thought this was back-ported to 1.8.7 my error.

R

--
It is change, continuing change, inevitable change, that is the
dominant factor in society today. No sensible decision can be made any
longer without taking into account not only the world as it is, but
the world as it will be ... ~ Isaac Asimov

Jesús Gabriel y Galán

1/31/2009 8:02:00 PM

On Sat, Jan 31, 2009 at 7:40 PM, Tsunami Scripter <lyon2003@lycos.com> wrote:
> Is it possible to modify an existing ruby string without creating a new
> one ?
>
> If for example I have the following code :
>
> x = "first string"
> x = "second string"
>
> between asigning values , the object_id() is different . Is there a
> possibility to modify the first string so that after the modifications
> the object_id will be the same ?

>> a = "first string"
=> "first string"
>> a.replace "second string"
=> "second string"
>> a
=> "second string"
>> a.object_id
=> 340702860
>> a.replace "third string"
=> "third string"
>> a.object_id
=> 340702860

> I would like to know how I could get to an empty string from "first
> string". I would like to know if a clear method exists,or something
> alike. I'm using ruby 1.8.7 .

a.replace ""

Jesus.

Tsunami Script

1/31/2009 8:12:00 PM

Just what I needed.

Thanks !
--
Posted via http://www.ruby-....

Julian Leviston

2/2/2009 6:01:00 AM

x.delete!(x) << "new value"

Before and after, the object id will be identical.

Sent from my iPhone

On 01/02/2009, at 5:40 AM, Tsunami Scripter <lyon2003@lycos.com> wrote:

> Is it possible to modify an existing ruby string without creating a
> new
> one ?
>
> If for example I have the following code :
>
> x = "first string"
> x = "second string"
>
> between asigning values , the object_id() is different . Is there a
> possibility to modify the first string so that after the modifications
> the object_id will be the same ?
>
> I would like to know how I could get to an empty string from "first
> string". I would like to know if a clear method exists,or something
> alike. I'm using ruby 1.8.7 .
> --
> Posted via http://www.ruby-....
>

ThoML

2/2/2009 7:08:00 AM

> Is it possible to modify an existing ruby string without creating a new
> one ?
> [...]
> between asigning values , the object_id() is different

I could be totally wrong but IMHO you're asking for two different
things.

As soon as you have something like "second string" in your code you
will create a second string. You can assign this to the variable (the
variable's value will have a different object_id) or replace its
content with that string (the variables value will have same object_id
as before but in between you created a second string).

3.times do
puts "---------"
x = "one".tap {|s| puts "one #{s.object_id}"}
p x, x.object_id
x.replace("two".tap {|s| puts "two #{s.object_id}"})
p x, x.object_id
end

comp.lang.ruby

ruby string question

Tsunami Script

Robert Dober

Tsunami Script

Robert Dober

Jesús Gabriel y Galán

Tsunami Script

Julian Leviston

ThoML

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