[texhax] Changing \DeclareOption of some other packages

[Uwe Lueck]

"Heiko Oberdiek" <heiko.oberdiek at googlemail.com> wrote 11.06.2011 16:59:14:
> On Sat, Jun 11, 2011 at 11:40:10PM +1000, Vafa Khalighi wrote:
>
>> Say a package has:
>>
>> \DeclareOption{rightcaption}{\def\right{right}}
>>
>> but in my package, I want to change that:
>>
>> \@ifpackageloaded{...}{\DeclareOption{rightcaption}{\def\right{Left}}{}
>>
>> How can you do that?
>
> You can't. If the package is loaded then the package options are processed
> and will not be executed later anymore.

You can (I bet). Redefine \@onefilewithoptions so that it uses
the \ProcessOptions command of the target package
as a hook to redefine the option before the options are actually
processed (and that hook also ensures restoring
the normal \ProcessOptions).

Such a redefinition may need to include a stack to
ensure that the \ProcessOptions of the target package
as opposed to \ProcessOptions commands of packages
that the target package loads actually is affected.

Nothing's impossible!

Cheers,

    Uwe Lück.