Right way to force the reloading of a file

throop has asked for the wisdom of the Perl Monks concerning the following question:

Once I have loaded a file using require, is there a clean way to reload the file?

I am running analyses on several 'families' of text files (Hazard reports, requirements documents, FMEAs.)

A Perl program analyzes the text-files. The program has many options, which I store in a HoH called %runSwitches. Each text-file needs a slightly different set of options.

Each document family has a default set of options, which must be tweaked for the particular text file.

Here's how I set it up: Each document has a short configuration file – documentName.pl. Each family has a file with a set of defaults – family_defaults.pl. The short configuration file loads the defaults, then asserts the tweeks:

require "family_default.pl";          # default values into %runSwitch
+es
%runSwitches = (%runSwitches,         # tweeks for a single document
                switch1 => 'tweek1',
                switch2 => 'tweek2');
[download]

This works fine. Except now I have a script that iterates though all the documents in a family. The first doc called loads the defaults and runs fine. The second file executes require "family_default.pl"; and does nothing, because family_default.pl is already in %INC. So the tweaks from the first file are still in effect, and I lose. I could

slurp the default file in and eval it each time, or
delete family_default.pl from %INC before loading each short config file.

Both of these seem like awkward hacks. Is there a better way to do this?

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Re: Right way to force the reloading of a file by ikegami (Patriarch) on Sep 14, 2009 at 20:46 UTC
Once I have loaded a file using require, is there a clean way to reload the file? Reloading the file is easy. It's unloading the effects of the previous version that relies on a lot of assumptions and limitations. But your question is wrong. The problem is your use of `require` to load something other than a module. You want `do`. That said, needing `do` is a sure sign of a bad design. This is no exception.	[reply] [d/l] [select]
Re: Right way to force the reloading of a file by moritz (Cardinal) on Sep 14, 2009 at 20:43 UTC
The clean way to solve your problem is to extract all the "interesting" code into a subroutine that takes configuration data as parameter(s), and put that in a module and export it. The existing script can then call this subroutine, as well as your recursive script. Perl 6 - links to (nearly) everything that is Perl 6.	[reply]
Re: Right way to force the reloading of a file by gloryhack (Deacon) on Sep 16, 2009 at 04:06 UTC
Rather than trying to outsmart Perl, outsmart the problem you're trying to solve. Were this mine to do, I'd start by having a good look at Config::Any for inspiration.	[reply]