I just discovered a new Operator in .Net 2.0…
the ?? operator.
One of the most anoing things to do when retrieving data, is checking for null values:
string myValue = dataReader.IsDBNull(2) ? string.Empty : dataReader.GetString(2);
But the ?? operator makes it a lot easier:
string myValue = dataReader.GetString(2)??string.Empty;
Why didn’t anybody tell me about this before?????
Read more here : http://msdn2.microsoft.com/en-us/library/ms173224(VS.80).aspx
Unfortuanly it doesn’t work on valuetypes.
So reader.GetInt(x) ?? wouldn’t work.
Do you have an idea what to do?
Seems to do quite the job as the || “double pipe” operator does in JavaScript and Ruby, and the ‘or’ operator in Python
//JavaScript:
var myVar = obj.returnNullValue() || “”;
#Ruby
my_var = obj.return_nil_value || “”
#Python
myvar = obj.return_none_value() or ”
Ruby even has several conditional assignment operators, f.ex. as shown in this function
def user_name
@user_name ||= “Anonymous Coward”
end
This either returns the name stored in the @user_name instance variable or , if it is null, assigns the name “Anonumous Coward” to the variable and returns it. Neat, huh? 🙂
Yeah, yeah, I know; these are all dynamic scripting languages, but it’s interesting to see how many of the dynamic language paradigms sneak into the static languages these days.
Cheers,
Kenneth
@priisholm: Hvordan faar du null coalescing til at vaere dynamic language baseret? 😉
At det samme ka la sig goere med en OR operator i perl, python, ruby, et. er en del af hvordan vaerdier og null-vaerdier blir haandeteret i nontype staerke entiteter i forskellige sprog 😉
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