Re: type aliases

David Johnston <polobo(at)yahoo(dot)com> writes:
> James Harper wrote
>> So suppose I wanted to implement myvarchar in C. In my _in function, how
>> do I know how big my column declaration is? Eg if someone tries to insert
>> 50 characters into my 42 character field, how do I get the declared length
>> and then tell postgres that the data to be inserted is too big?

> There is no current way for a function body to examine the type modifiers of
> its input, domain or otherwise.

Actually the point here is to know the required type modifier of the
*output*. Type input functions do get passed the target typmod, as a
separate argument. See varcharin() for an example.

regards, tom lane