That will work fine (no exception). Extension methods don’t use virtual calls (i.e. it uses the “call” il instruction, not “callvirt”) so there is no null check unless you write it yourself in the extension method. This is actually useful in a few cases: public static bool IsNullOrEmpty(this string value) { return string.IsNullOrEmpty(value); } public … Read more
The compiler replaces null comparisons with a call to HasValue, so there is no real difference. Just do whichever is more readable/makes more sense to you and your colleagues.
On the actual behavior, there is no difference. They all return None and that’s it. However, there is a time and place for all of these. The following instructions are basically how the different methods should be used (or at least how I was taught they should be used), but they are not absolute rules … Read more
If you are always expecting to find a value then throw the exception if it is missing. The exception would mean that there was a problem. If the value can be missing or present and both are valid for the application logic then return a null. More important: What do you do other places in … Read more
You guys are making this too hard. PowerShell handles this quite elegantly e.g.: > $str1 = $null > if ($str1) { ‘not empty’ } else { ’empty’ } empty > $str2 = ” > if ($str2) { ‘not empty’ } else { ’empty’ } empty > $str3 = ‘ ‘ > if ($str3) { ‘not … Read more
You should be using IllegalArgumentException (IAE), not NullPointerException (NPE) for the following reasons: First, the NPE JavaDoc explicitly lists the cases where NPE is appropriate. Notice that all of them are thrown by the runtime when null is used inappropriately. In contrast, the IAE JavaDoc couldn’t be more clear: “Thrown to indicate that a method … Read more
You could do this: Name.objects.exclude(alias__isnull=True) If you need to exclude null values and empty strings, the preferred way to do so is to chain together the conditions like so: Name.objects.exclude(alias__isnull=True).exclude(alias__exact=””) Chaining these methods together basically checks each condition independently: in the above example, we exclude rows where alias is either null or an empty string, … Read more
Let’s evaluate the parsing of each: http://jsfiddle.net/brandonscript/Y2dGv/ var json1 = ‘{}’; var json2 = ‘{“myCount”: null}’; var json3 = ‘{“myCount”: 0}’; var json4 = ‘{“myString”: “”}’; var json5 = ‘{“myString”: “null”}’; var json6 = ‘{“myArray”: []}’; console.log(JSON.parse(json1)); // {} console.log(JSON.parse(json2)); // {myCount: null} console.log(JSON.parse(json3)); // {myCount: 0} console.log(JSON.parse(json4)); // {myString: “”} console.log(JSON.parse(json5)); // {myString: “null”} … Read more
I think the most efficient way to test for “value is null or undefined” is if ( some_variable == null ){ // some_variable is either null or undefined } So these two lines are equivalent: if ( typeof(some_variable) !== “undefined” && some_variable !== null ) {} if ( some_variable != null ) {} Note 1 … Read more
How do I check a variable if it’s null or undefined… Is the variable null: if (a === null) // or if (a == null) // but see note below …but note the latter will also be true if a is undefined. Is it undefined: if (typeof a === “undefined”) // or if (a === … Read more