Le 02/10/14 à 13h32, "Julien RIVAUD (_FrnchFrgg_)"
<[log in to unmask]> a écrit :

> Le 02/10/2014 09:22, Ulrike Fischer a écrit :
>> Beside this there is also the timing problem Joseph mentioned: when
>> should be tested if a key has been used? It is obviously not the key
>> code of the key that can do it. So imho you are not looking for a
>> .required property but a .enableifsettest property which adds and
>> sets some boolean which you can later check.
> Or better yet, use an initial value for your property that unambiguously
> represents "not set", and validate that at the beginning.
> Since you need to have an extra step to check if the required properties have
> been set, you can as well use a token list to store the value instead of
> directly an int for instance, and first check if it is your special "not set"
> value, then cast it to integer yourself.

Indeed. Maybe I was wrong, but it came to my mind that I wouldn't be the
only one who needs such checks. And, instead of leaving each one hacking
this by hands more or less properly, a general LaTeX3 frame could be