There are multiple ways to do this. You can use a sub query: SET @some_var = (SELECT COUNT(*) FROM mytable); (like your original, just add parenthesis around the query) or use the SELECT INTO syntax to assign multiple values: SELECT COUNT(*), MAX(col) INTO @some_var, @some_other_var FROM tab; The sub query syntax is slightly faster (I … Read more
You should never expect them to outperform assignments. The reason is, the compiler will use memcpy anyway when it thinks it would be faster (if you use optimize flags). If not and if the structure is reasonable small that it fits into registers, direct register manipulation could be used which wouldn’t require any memory access … Read more
From the JLS 5.2 Assignment Conversion In addition, if the expression is a constant expression (ยง15.28) of type byte, short, char, or int: – A narrowing primitive conversion may be used if the type of the variable is byte, short, or char, and the value of the constant expression is representable in the type of … Read more
All you need to do is make your val side (left of the =) compatible with your initializer (right of the =): scala> val Array(x, y, z) = “XXX,YYY,ZZZ”.split(“,”) x: java.lang.String = XXX y: java.lang.String = YYY z: java.lang.String = ZZZ As you expected, a scala.MatchError will be thrown at runtime if the array size … Read more
From the Assignment statements documentation: An assignment statement evaluates the expression list (remember that this can be a single expression or a comma-separated list, the latter yielding a tuple) and assigns the single resulting object to each of the target lists, from left to right. You have two assignment target lists; a, b, and a[b], … Read more
Try some thing like (set! (.-property foo) 5)
It’s a conditional assignment. From here: x = find_something() #=>nil x ||= “default” #=>”default” : value of x will be replaced with “default”, but only if x is nil or false x ||= “other” #=>”default” : value of x is not replaced if it already is other than nil or false
To answer your question, no. Assignments to doubles are not guarenteed to be atomic. The docs are available here. Basically, <= 32-bit built-in types are atomic, >= 64-bit types aren’t. For atomic operations on 64bit types, you can use the methods on System.Threading.Interlocked
Assigning to arguments indicies will only change the associated argument value (let’s call it the n-th argument) if the function was called with at least n arguments. The arguments object’s numeric-indexed properties are essentially setters (and getters): http://es5.github.io/#x10.6 Italics in the below are my comments on how the process relates to the question: (Let) args … Read more