I forgot to CC the group.. but now I realized, when I originally read
his post I thought he was looking to define a variable once and then
leave it read only for the rest of the program execution which is why I
suggested the following. However, I realize now that he's just trying
to avoid prefixing the symbols with '&'.
This is a design issue more than anything. As has been stated,
constants defined at run time aren't really "constant". Why do you need
to do this anyways?
On Tue, Mar 02, 2004 at 08:20:29PM -0500, Brad Lhotsky wrote:
> ----- Forwarded message from Brad Lhotsky <[EMAIL PROTECTED]> -----
>
> From: Brad Lhotsky <[EMAIL PROTECTED]>
> To: Rodent of Unusual Size <[EMAIL PROTECTED]>
> Subject: Re: defining 'constants' at run time
> Date: Tue, 2 Mar 2004 14:01:06 -0500
> User-Agent: Mutt/1.4i
> Message-ID: <[EMAIL PROTECTED]>
>
> Any reason why it has to be a constant? I'm pretty sure you could
> either find or write a Tie:: class that would only allow you to set the
> value of a variable, or hash key once. That might be a more
> maintainable solution.
>
> The code for this wouldn't be difficult if it doesn't already exist:
>
> my $var = undef;
> tie $var, 'Tie::Constant';
>
> $var = 250;
>
> $var = 1; # warning attempt to modify read-only value!
>
> print "$var\n"; # '250\n';
>
> ?
>
> On Tue, Mar 02, 2004 at 05:42:07AM -0500, Rodent of Unusual Size wrote:
> > tell me to piss off for asking here, if you like, but i'm not on
> > any other perl lists due to traffic. besides, the responses and
> > advice here have been higher quality. :-)
> >
> > i want to be able to define 'constants' in a module at run time,
> > rather than at compile time. 'use constant' does it too early.
> > for example:
> >
> > use Foo;
> > my $foo = new Foo;
> > $foo->mkconst('DOH', 25);
> > printf("DOH=%d\n", DOH);
> >
> > the result i'm looking for is 'DOH=25' on stdout. however,
> > all i've managed to get is either an error about DOH being a
> > non-integer, or an unopened filehandle. i've tried things
> > like having mkconst() do
> >
> > my $name = caller() . "::$_[0]";
> > eval("\*$name = sub () { $_[1]; }");
> >
> > and that will work -- IFF the caller refers to DOH as &DOH.
> >
> > evidently the usage of DOH in the caller has already been fetched
> > from the symbol table (and found wanting) before the method has
> > been called. is there any way to defeat that?
> >
> > (i hope i'm explaining this lucidly.)
> > --
> > #ken P-)}
> >
> > Ken Coar, Sanagendamgagwedweinini http://Ken.Coar.Org/
> > Author, developer, opinionist http://Apache-Server.Com/
> >
> > "Millennium hand and shrimp!"
> >
> >
>
> --
> Brad Lhotsky <[EMAIL PROTECTED]>
>
> ----- End forwarded message -----
>
> --
> Brad Lhotsky <[EMAIL PROTECTED]>
--
Brad Lhotsky <[EMAIL PROTECTED]>
