Frozen string problem, but I haven't frozen anything?

ruby-talk
1

Hi,

I am new to Ruby. I’m trying to get some Ruby scripts going to manage
or CVS log message emails. (I haven’t written them myself, got them
from the web.)

I get:
/home/cvs/repository/CVSROOT/commitinfo.rb:26:in `tr_s!’: can’t modify
frozen string (TypeError)
from /home/cvs/repository/CVSROOT/commitinfo.rb:26

I’ve done some reading, and I suspect I understand what the frozen
string issue is about. The problem is, I don’t see how/why this string
is frozen? Here is the relevant code snippet:

···

if ARGV.size < 4
puts "Usage: #{$0} CVSROOT USER modulepath file1 [file2…]"
exit 1 # No way!
end

$cvsroot, $cvsuser, $modulepath, *$cvsfiles = *ARGV

$cvsroot.tr_s!(’/’, ‘/’)
$modulepath.tr_s!(’/’, ‘/’)

The two lines using ‘tr_s!’ causes the problem, but I don’t see
how/why $cvsroot or $modulepath is ‘frozen’? Might it be due to the
fact that they are passed to the script, i.e. some global/local scope
issue?

Regards,
Lourens

2

LC Geldenhuys wrote:

Hi,

I am new to Ruby. I’m trying to get some Ruby scripts going to manage
or CVS log message emails. (I haven’t written them myself, got them
from the web.)

I get:
/home/cvs/repository/CVSROOT/commitinfo.rb:26:in `tr_s!': can’t modify
frozen string (TypeError)
from /home/cvs/repository/CVSROOT/commitinfo.rb:26

I’ve done some reading, and I suspect I understand what the frozen
string issue is about. The problem is, I don’t see how/why this string
is frozen? Here is the relevant code snippet:

if ARGV.size < 4
puts “Usage: #{$0} CVSROOT USER modulepath file1 [file2…]”
exit 1 # No way!
end

$cvsroot, $cvsuser, $modulepath, *$cvsfiles = *ARGV

$cvsroot.tr_s!(‘/’, ‘/’)
$modulepath.tr_s!(‘/’, ‘/’)

The two lines using ‘tr_s!’ causes the problem, but I don’t see
how/why $cvsroot or $modulepath is ‘frozen’? Might it be due to the
fact that they are passed to the script, i.e. some global/local scope
issue?

you can’t modify values in ARGV. you have to copy the values.

3

Thanks, the following now seems to work.

$cvsroot_in, $cvsuser, $modulepath_in, *$cvsfiles = *ARGV

$cvsroot = $cvsroot_in.dup
$modulepath = $modulepath_in.dup

$cvsroot.tr_s!(‘/’, ‘/’)
$modulepath.tr_s!(‘/’, ‘/’)

Cheers,
Lourens

···

On Tue, 17 Feb 2004 18:04:00 +0900, Emmanuel Touzery emmanuel.touzery@wanadoo.fr wrote:

LC Geldenhuys wrote:

Hi,

I am new to Ruby. I’m trying to get some Ruby scripts going to manage
or CVS log message emails. (I haven’t written them myself, got them
from the web.)

I get:
/home/cvs/repository/CVSROOT/commitinfo.rb:26:in `tr_s!': can’t modify
frozen string (TypeError)
from /home/cvs/repository/CVSROOT/commitinfo.rb:26

I’ve done some reading, and I suspect I understand what the frozen
string issue is about. The problem is, I don’t see how/why this string
is frozen? Here is the relevant code snippet:

if ARGV.size < 4
puts “Usage: #{$0} CVSROOT USER modulepath file1 [file2…]”
exit 1 # No way!
end

$cvsroot, $cvsuser, $modulepath, *$cvsfiles = *ARGV

$cvsroot.tr_s!(‘/’, ‘/’)
$modulepath.tr_s!(‘/’, ‘/’)

The two lines using ‘tr_s!’ causes the problem, but I don’t see
how/why $cvsroot or $modulepath is ‘frozen’? Might it be due to the
fact that they are passed to the script, i.e. some global/local scope
issue?

you can’t modify values in ARGV. you have to copy the values.

4

“LC Geldenhuys” lcgeldenhuys@hotmail.com schrieb im Newsbeitrag
news:s26430l9o2e34veibgqpc76kvvnn67ras1@4ax.com…

LC Geldenhuys wrote:

Hi,

I am new to Ruby. I’m trying to get some Ruby scripts going to manage
or CVS log message emails. (I haven’t written them myself, got them
from the web.)

I get:
/home/cvs/repository/CVSROOT/commitinfo.rb:26:in `tr_s!': can’t modify
frozen string (TypeError)
from /home/cvs/repository/CVSROOT/commitinfo.rb:26

I’ve done some reading, and I suspect I understand what the frozen
string issue is about. The problem is, I don’t see how/why this string
is frozen? Here is the relevant code snippet:

if ARGV.size < 4
puts “Usage: #{$0} CVSROOT USER modulepath file1 [file2…]”
exit 1 # No way!
end

$cvsroot, $cvsuser, $modulepath, *$cvsfiles = *ARGV

$cvsroot.tr_s!(‘/’, ‘/’)
$modulepath.tr_s!(‘/’, ‘/’)

The two lines using ‘tr_s!’ causes the problem, but I don’t see
how/why $cvsroot or $modulepath is ‘frozen’? Might it be due to the
fact that they are passed to the script, i.e. some global/local scope
issue?

you can’t modify values in ARGV. you have to copy the values.

Thanks, the following now seems to work.

$cvsroot_in, $cvsuser, $modulepath_in, *$cvsfiles = *ARGV

$cvsroot = $cvsroot_in.dup
$modulepath = $modulepath_in.dup

$cvsroot.tr_s!(‘/’, ‘/’)
$modulepath.tr_s!(‘/’, ‘/’)

Why don’t you just do

$cvsroot_in, $cvsuser, $modulepath_in, *$cvsfiles = *ARGV

$cvsroot.tr_s(‘/’, ‘/’)
$modulepath.tr_s(‘/’, ‘/’)

? And, why do you use global variables at all?

Regards

robert
···

On Tue, 17 Feb 2004 18:04:00 +0900, Emmanuel Touzery > emmanuel.touzery@wanadoo.fr wrote:

5

You probably meant:
$cvsroot = $cvsroot_in.tr_s(‘/’, ‘/’)
$modulepath = $modulepath_in.tr_s(‘/’, ‘/’)

but how about:
$cvsroot, $cvsuser, $modulepath, *$cvsfiles = *ARGV.map{|a|a.dup}

this unfreezes everything automagically.

Cheers,
Mark

···

On Feb 17, 2004, at 6:14 AM, Robert Klemme wrote:

Why don’t you just do

$cvsroot_in, $cvsuser, $modulepath_in, *$cvsfiles = *ARGV

$cvsroot.tr_s(‘/’, ‘/’)
$modulepath.tr_s(‘/’, ‘/’)

6

“Mark Hubbart” discord@mac.com schrieb im Newsbeitrag
news:3AA77270-6182-11D8-B680-000502FDD5CC@mac.com…

Why don’t you just do

$cvsroot_in, $cvsuser, $modulepath_in, *$cvsfiles = *ARGV

$cvsroot.tr_s(‘/’, ‘/’)
$modulepath.tr_s(‘/’, ‘/’)

You probably meant:
$cvsroot = $cvsroot_in.tr_s(‘/’, ‘/’)
$modulepath = $modulepath_in.tr_s(‘/’, ‘/’)

Yes. Thanks for correcting that.

but how about:
$cvsroot, $cvsuser, $modulepath, *$cvsfiles = *ARGV.map{|a|a.dup}

this unfreezes everything automagically.

As always there are tons of ways to do things with Ruby. Which is good.
:slight_smile:

Regards

robert
···

On Feb 17, 2004, at 6:14 AM, Robert Klemme wrote: