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[] and {} are blessable anonymous refs. I.e., both

bless [], 'Foo';

and

bless {}, 'Bar';

Is there a way to get a blessable anonymous ref to a scalar? The
typical example of an anonymous scalar ref is something like \3,
but if one tries to bless such a ref, the compiler chokes on the
"attempt to modify a read-only value".

TIA,

jill

--
To s&e^n]d me m~a}i]l r%e*m?o\v[e bit from my a|d)d:r{e:s]s.

Also sprach J Krugman:

> [] and {} are blessable anonymous refs. I.e., both
>
> bless [], 'Foo';
>
> and
>
> bless {}, 'Bar';
>
> Is there a way to get a blessable anonymous ref to a scalar? The
> typical example of an anonymous scalar ref is something like \3,
> but if one tries to bless such a ref, the compiler chokes on the
> "attempt to modify a read-only value".

Perl lacks an anonymous scalar reference constructor, so in order to be
not read-only, the scalar ref must initially refer to a readable scalar
which then necessarily has a name.

Tassilo
--
use bigint;
$n=71423350343770280161397026330337371139054411854 220053437565440;
$m=-8,;;$_=$n&(0xff)<<$m,,$_>>=$m,,print+chr,,while(($ m+=<=200);

On Sun, 13 Mar 2005 12:04:11 +0000, J Krugman wrote:
> Is there a way to get a blessable anonymous ref to a scalar? The
> typical example of an anonymous scalar ref is something like \3,
> but if one tries to bless such a ref, the compiler chokes on the
> "attempt to modify a read-only value".

bless \do { my $foo }, 'Foo';

--
Peter Scott
http://www.perlmedic.com/
http://www.perldebugged.com/

In <d11a7r$8rm$> J Krugman <> writes:

>[] and {} are blessable anonymous refs. I.e., both

> bless [], 'Foo';

>and

> bless {}, 'Bar';

>Is there a way to get a blessable anonymous ref to a scalar? The
>typical example of an anonymous scalar ref is something like \3,
>but if one tries to bless such a ref, the compiler chokes on the
>"attempt to modify a read-only value".

\$_ is not exactly anonymous (after all, it's the scalar formerly
known as foo), but at least you wouldn't have to go through the
mind-scarring experience of having to come up with a name for no
good reason.

kj

--
NOTE: In my address everything before the first period is backwards;
and the last period, and everything after it, should be discarded.

kj wrote:

> In <d11a7r$8rm$> J Krugman <> writes:
>
>
>>[] and {} are blessable anonymous refs. I.e., both
>
>
>>bless [], 'Foo';
>
>
>>and
>
>
>>bless {}, 'Bar';
>
>
>>Is there a way to get a blessable anonymous ref to a scalar? The
>>typical example of an anonymous scalar ref is something like \3,
>>but if one tries to bless such a ref, the compiler chokes on the
>>"attempt to modify a read-only value".
>
>
> \$_ is not exactly anonymous (after all, it's the scalar formerly
> known as foo), but at least you wouldn't have to go through the
> mind-scarring experience of having to come up with a name for no
> good reason.

Boggle!

But then you are blessing \$foo (or whatever $_ happens to be aliased to
at the time). That's hideous!

In <d12530$t0g$> Brian McCauley <> writes:

>kj wrote:

>> In <d11a7r$8rm$> J Krugman <> writes:
>>
>>
>>>[] and {} are blessable anonymous refs. I.e., both
>>
>>
>>>bless [], 'Foo';
>>
>>
>>>and
>>
>>
>>>bless {}, 'Bar';
>>
>>
>>>Is there a way to get a blessable anonymous ref to a scalar? The
>>>typical example of an anonymous scalar ref is something like \3,
>>>but if one tries to bless such a ref, the compiler chokes on the
>>>"attempt to modify a read-only value".
>>
>>
>> \$_ is not exactly anonymous (after all, it's the scalar formerly
>> known as foo), but at least you wouldn't have to go through the
>> mind-scarring experience of having to come up with a name for no
>> good reason.

>Boggle!

>But then you are blessing \$foo (or whatever $_ happens to be aliased to
>at the time). That's hideous!

Aw, c'mon, it's not so bad! All we need is one of all those scalars
who are standing around doing little or nothing, to serve as a
reference in a little blessing ceremony. Now, is that so hard?

OK, how about \$% ?

kj
--
NOTE: In my address everything before the first period is backwards;
and the last period, and everything after it, should be discarded.

Peter Scott <> wrote in comp.lang.perl.misc:
> On Sun, 13 Mar 2005 12:04:11 +0000, J Krugman wrote:
> > Is there a way to get a blessable anonymous ref to a scalar? The
> > typical example of an anonymous scalar ref is something like \3,
> > but if one tries to bless such a ref, the compiler chokes on the
> > "attempt to modify a read-only value".
>
> bless \do { my $foo }, 'Foo';

Why the do{}?

bless \ my $foo, 'Foo';

works just as well.

Anno

J Krugman <> wrote in comp.lang.perl.misc:
>
>
>
> [] and {} are blessable anonymous refs. I.e., both
>
> bless [], 'Foo';
>
> and
>
> bless {}, 'Bar';
>
> Is there a way to get a blessable anonymous ref to a scalar? The
> typical example of an anonymous scalar ref is something like \3,
> but if one tries to bless such a ref, the compiler chokes on the
> "attempt to modify a read-only value".

bless \ "$_", 'Foo' for 3;

Anno

Abigail <> wrote in comp.lang.perl.misc:
> Anno Siegel () wrote on MMMMCCXIII
> September MCMXCIII in <URL:news:d13hgq$9he$>:
> () Peter Scott <> wrote in comp.lang.perl.misc:
> () > On Sun, 13 Mar 2005 12:04:11 +0000, J Krugman wrote:
> () > > Is there a way to get a blessable anonymous ref to a scalar? The
> () > > typical example of an anonymous scalar ref is something like \3,
> () > > but if one tries to bless such a ref, the compiler chokes on the
> () > > "attempt to modify a read-only value".
> () >
> () > bless \do { my $foo }, 'Foo';
> ()
> () Why the do{}?
> ()
> () bless \ my $foo, 'Foo';
> ()
> () works just as well.
>
>
> Without the do, the scalar isn't anonymous - it's known as '$foo'.
> The do creates a scope, and the scalar no longer has a name.

Oh, okay...

Usually this happens in a ->new method (under whatever name), whose
body already provides a sufficiently small scope.

Anno

kj wrote:

> In <d12530$t0g$> Brian McCauley <> writes:
>
>
>>kj wrote:
>
>
>>>In <d11a7r$8rm$> J Krugman <> writes:
>>>
>>>
>>>
>>>>[] and {} are blessable anonymous refs. I.e., both
>>>
>>>
>>>>bless [], 'Foo';
>>>
>>>
>>>>and
>>>
>>>
>>>>bless {}, 'Bar';
>>>
>>>
>>>>Is there a way to get a blessable anonymous ref to a scalar? The
>>>>typical example of an anonymous scalar ref is something like \3,
>>>>but if one tries to bless such a ref, the compiler chokes on the
>>>>"attempt to modify a read-only value".
>>>
>>>
>>>\$_ is not exactly anonymous (after all, it's the scalar formerly
>>>known as foo), but at least you wouldn't have to go through the
>>>mind-scarring experience of having to come up with a name for no
>>>good reason.
>
>
>>Boggle!
>
>
>>But then you are blessing \$foo (or whatever $_ happens to be aliased to
>>at the time). That's hideous!
>
>
> Aw, c'mon, it's not so bad!

No, it really is very very bad.


for ( @some_array ) {
my $object = SomeThing->new; # Corrupts @some_array
}

sub SomeThing::new {
bless \$_;
}

> All we need is one of all those scalars
> who are standing around doing little or nothing, to serve as a
> reference in a little blessing ceremony.

No, this is completely bogus. You need a modifyable scalar value that
is not used past, present, or future for anything else - not even
subsquent iterations of the same code.

> Now, is that so hard?

No it's no hard, it's trivial do{\my $o}.

> OK, how about \$% ?

Now you are just being silly.