• berni (11/18) Sep 11 2018 I call this function using enforce(extract_list(some_argument)).

berni <someone somemail.de> writes:

I've got the folling function which returns a RegexMatch!string:

 auto extract_list(const string entry)
 {
     // check if entry is valid
 
     return matchAll(entry, some_regex);
 }

I call this function using enforce(extract_list(some_argument)). 
I think, that enforce is quite useless in this version. But I'd 
like to add a check, if entry is valid in the 
extract_list-function, something like:

 if (!matchFirst(entry, other_regex)) return null;

That doesn't work, because I cannot cast null to 
RegexMatch!string (I don't understand why). What works is to 
create a string[] from the result of matchAll (using map and 
array) and use that array instead of the range. Now I can return 
null too.

Is there a way to accomplish this?