Allow older versions of perltidy to use newer .perltidyrc files

[jidanni]

Here I can use my .emacs file safely, no matter what version of emacs
I'm using.

$ cat .emacs
(and(functionp 'native-compile-prune-cache)
    (native-compile-prune-cache))

It would be great if .perltidyrc had a similar mechanism,
so I could say e.g.,

--if-implemented-yet -- --want-trailing-commas=1
--if-implemented-yet -- --add-trailing-commas

to avoid causing

Unknown option: want-trailing-commas
Unknown option: add-trailing-commas
Error in this config file: /home/jidanni/.perltidyrc
Use -npro to ignore this file, -h for help'

in the case I had used my newer .perltidyrc on a machine with an older perltidy.

Wait, https://www.perlmonks.org/?node_id=1165148 shows how to do it in
general in perl, so there could be something similar for .perltidyrc,
other than needing to have a different file for each different version
of perltidy.

Anyway, with my --if-implemented-yet, the user wouldn't even have to look up specific version numbers.

[shancock9]

A scheme like this would have had to have been implemented long ago to be
useful.

It would be possible to write a replacement script for the perltidy binary
which filters out unrecognized parameters from a .perltidyrc and sends a
modified version to the Perl::Tidy module.

But if a new binary is going to be involved, a simpler thing to do on a system
that you do not want to update would be to make a special binary with the latest
version and put it in your personal bin directory. To do this,

• download and unzip the latest tarball in a temporary area
• cd into the new folder
• enter ./pm2pl
• this creates a single file called something like perltidy-20240511.pl
• move and rename this to something more convenient, perhaps ~/bin/perltidy-latest.pl

The installed version of the Perl::Tidy module will be unchanged, but the new
binary does not use it

[jidanni]

A scheme like this would have had to have been implemented long ago to be
useful.

Never too late to start :-).

[oalders]

This seems like a pretty niche case. I don't think it's unreasonable to make this the end user's problem to solve.

[shancock9]

I've tentatively added an option to do this by filtering a config file as follows:
if a line in the config file begins with three dashes followed by a parameter name
(rather than two), then it will be removed if the parameter is not known. Otherwise,
a dash will be removed to make the line valid. Older versions of perltidy will
immediately stop if a parameter has three dashes.

I don't know if this will be very useful, since I don't anticipate adding many more
options to perltidy, but it was a simple change.