How to share "constant" among many modules

[rubis]

Hi,

I want to share the same constants among 3 modules e.g. Module A, B and C use the same constant $x. Could u pls suggest me how to do it?

Thanks,

 

[justice41]

There is an article at perl.com about this very thing.

http://www.perl.com/pub/a/2002/04/23/mod_perl.html

Enjoy!

jaa

 

[rubis]

There is only the method of how to share the variable but what I want to share is "constant".. any suggestion pls??

 

[justice41]

Oh so you mean, for example, for

use constant three => 3;

you want each module to share the same 3 rather than each using their own individual 3?

jaa

 

[justice41]

Oops, I hit 'submit' instead of 'preview'. For what you are trying to do you should probably use a conf file that each module reads.

jaa

 

[PaulTEG]

How about setting up a symbolic link, and reading the value of that?

 

[rubis]

To Justice41...

yes. Many modules use the same constant so I don't want to declare each constant seperately in each module as it is not a good idea to modify it later on. For the config file, u mean I should read the value from the file and then keep it in the constant variable?? Is there a way to declare the constant in one module (let say the module that keeps all share constants) and then the other module can see these constants??

To PaulTEG...

You mean set the symbolic link in one module and let the other modules read it??

 

[PaulTEG]

Legacy of VMS programming
We used logicals (symlinks) to store filenames, and by shelling a process to change the value we could switch between different datasets using the same logicals in the code. Later we used logicals to point to printers, and finally environemnt variables.
The logicals (in VMS) were set in the startup script for the machine, were visible to all processes on the machine with the correct rights.
The symlink might map to a file, but if the constant files are created what odds.
This probably wouldn't work on a Win32 platform, actually on further consideration without serious admin rights to the server it probably wouldn't work at all
Regards

 

[PaulTEG]

So many choices, so little time

create a perl script to hold your constants, called const.pl
Initialise your constants, and then in modules A, B and C

add the following line

require const.pl

HTH