[texhax] How do you make * macros?

[Uwe Lueck]

"Lars Madsen" <daleif at imf.au.dk>, 22.10.2010 23:17:53:
>Quoting Michael Barr :
>
>> Assuming I have a macro \xxx that does something, how do I make  
>> \xxx* that does something slightly different?  If think I make  
>> something using \@ifnextchar, but there is probably an "official"  
>> way of doing it that I don't see in the Companion (1994 edition).
>>
>> Michael
>
>besides the constructions already mentioned I'd like to mention xparse as well

I did want to mention xparse, but it was not available via 

    http://ctan.org/pkg/xparse

so I considered it too difficult ... 

Cheers, 

    Uwe.