C's static equivalent - Ruby

[KONTRA Gergely]

Hi!

Is there something similar to C's static keyword?
I want a single function, which has to access and modify a permanent
variable. Any solution without bundling the function to a class?

Gergo
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[ts]

>>>>> "K" == KONTRA Gergely <kgergelymlabdial.hit.bme.hu> writes:

K> Is there something similar to C's static keyword?
K> I want a single function, which has to access and modify a permanent
K> variable. Any solution without bundling the function to a class?

Use a closure

Guy Decoux

[KONTRA Gergely]

On 0807, ts wrote:

> >>>>> "K" == KONTRA Gergely <kgergelymlabdial.hit.bme.hu> writes:

>
> K> Is there something similar to C's static keyword?
> K> I want a single function, which has to access and modify a permanent
> K> variable. Any solution without bundling the function to a class?
> Use a closure

Could you be more verbose? Eg. how to print out how many times a
function was called.

Gergo
--
+-[ Kontra, Gergely<kgergelymcl.hu> PhD student Room IB113 ]---------+
| [url]http://www.mcl.hu/~kgergely[/url] "Olyan langesz vagyok, hogy |
| Mobil:(+36 20) 356 9656 ICQ: 175564914 poroltoval kellene jarnom" |
+-- Magyar php mirror es magyar php dokumentacio: [url]http://hu.php.net[/url] --+

[ts]

>>>>> "K" == KONTRA Gergely <kgergelymlabdial.hit.bme.hu> writes:

>> Use a closure

K> Could you be more verbose? Eg. how to print out how many times a

in ruby, yes. in english, no :-)

K> function was called.

svg% cat b.rb
#!/usr/bin/ruby
def test1
a = 10
proc { a += 1; puts a }
end

class Object
define_method(:tt, test1)
end

tt
tt

uu = test1
uu[]
uu[]
svg%

svg% b.rb
11
12
11
12
svg%



Guy Decoux

[djd15@cwru.edu]

More or less:

def make_closure
perm_variable = 0
return proc {
perm_variable += 1
puts "I have been called ", perm_variable, " times."
}
end

def use_closure
fun = make_closure
fun.call
fun.call
fun.call
end

use_closure

Should print out

I have been called 1 times.
I have been called 2 times.
I have been called 3 times.

However, each time you call make_closure, it returns a separate context, so:

def use_closure2
fun1 = make_closure
fun2 = make_closure

fun1.call
fun2.call
fun1.call
end

use_closure2

Should print:

I have been called 1 times.
I have been called 1 times.
I have been called 2 times.

Because fun1 and fun2 store two separate states of perm_variable.
At least that's my understanding of closures.

As far as I know, there's nothing quite like C's static
in Ruby, since there's no way to make a variable local
in scope to a function, but persistant in state over all
calls to that function (at least that I know of).

- Dan

----- Original Message -----
From: KONTRA Gergely <kgergelymlabdial.hit.bme.hu>
Date: Thursday, August 7, 2003 9:59 am
Subject: Re: C's static equivalent

> On 0807, ts wrote:

> > >>>>> "K" == KONTRA Gergely <kgergelymlabdial.hit.bme.hu> writes:

> >
> > K> Is there something similar to C's static keyword?
> > K> I want a single function, which has to access and modify a

> permanent> K> variable. Any solution without bundling the function
> to a class?

> > Use a closure

> Could you be more verbose? Eg. how to print out how many times a
> function was called.
>
> Gergo
> --
> +-[ Kontra, Gergely<kgergelymcl.hu> PhD student Room IB113 ]------
> ---+
> | [url]http://www.mcl.hu/~kgergely[/url] "Olyan langesz vagyok,
> hogy |
> | Mobil:(+36 20) 356 9656 ICQ: 175564914 poroltoval kellene
> jarnom" |
> +-- Magyar php mirror es magyar php dokumentacio:
> [url]http://hu.php.net[/url] --+
>
>

[Brian Candler]

On Thu, Aug 07, 2003 at 11:18:17PM +0900, [email]djd15cwru.edu[/email] wrote:

> As far as I know, there's nothing quite like C's static
> in Ruby, since there's no way to make a variable local
> in scope to a function, but persistant in state over all
> calls to that function (at least that I know of).

A C 'static' variable is just a global variable with a lexically local
scope, so a class variable (count += 1) is probably the closest
equivalent. The scope extends to the whole object though, not just the
method.

Regards,

Brian.

[Hal E. Fulton]

----- Original Message -----
From: "ts" <decouxmoulon.inra.fr>
To: "ruby-talk ML" <ruby-talkruby-lang.org>
Cc: <ruby-talkruby-lang.org>
Sent: Thursday, August 07, 2003 9:06 AM
Subject: Re: C's static equivalent

> >>>>> "K" == KONTRA Gergely <kgergelymlabdial.hit.bme.hu> writes:

>

> >> Use a closure

> K> Could you be more verbose? Eg. how to print out how many times a
>
> in ruby, yes. in english, no :-)

It would be worthwhile for all of us to
learn French in order to learn more of
your wisdom. :)

Hal

--
Hal Fulton
[email]hal9000hypermetrics.com[/email]

[Josef 'Jupp' Schugt]

Saluton!

* Hal E. Fulton; 2003-08-07, 17:05 UTC:

> It would be worthwhile for all of us to learn French in order to
> learn more of your wisdom. :)

Si on ne doit pas répondre en français :->
As long as we are not required to answer in french ...

Gis,

Josef 'Jupp' Schugt
--
N'attribuez jamais à la malice ce que l'incompétence explique !
-- Napoléon