Where are the short-circuiting operators in ActionScript/JavaScript?
Like VB has operators AndAlso and OrElse, that perform short-circuiting logical conjunction, where can equivalent operators be found in JS / AS? ...
short-circuiting
Why is short-circuiting not the default behavior in VB?
VB has operators AndAlso and OrElse, that perform short-circuiting logical conjunction. Why is this not the default behavior of And and Or expressions since short-circuiting is useful in every case. Strangely, this is contrary to most languages where && and || perform short-circuiting. ...
How to avoid short-circuit evaluation on
I'm working with Ruby on Rails and would like to validate two different models : if (model1.valid? && model2.valid?) ... end However, "&&" operator uses short-circuit evaluation (i.e. it evaluates "model2.valid?" only if "model1.valid?" is true), which prevents model2.valids to be executed if model1 is not valid. Is there an equivale...
COALESCE - guaranteed to short-circuit?
From this question, a neat answer about using COALESCE to simplify complex logic trees. I considered the problem of short circuiting. For instance, in functions in most languages, arguments are fully evaluated and are then passed into the function. In C: int f(float x, float y) { return x; } f(a, a / b) ; // This will result in ...
NULL parameters in scalar UDFs on MSSQL
The option "RETURNS NULL ON NULL INPUT" for a scalar UDF (see CREATE FUNCTION) stops the function body executing if the parameter is null and simply returns NULL. That is, it short circuits. Does anyone know how it handles multiple parameters? It would be useful to short circuit a function call with multiple parameters, say if the fir...
Calling methods inside if() - C#
I have a couple of methods that return a bool depending on their success, is there anything wrong with calling those methods inside of the IF() ? //&& makes sure that Method2() will only get called if Method1() returned true, use & to call both methods if(Method1() && Method2()) { // do stuff if both methods returned TRUE } Method...
Is short-circuiting boolean operators mandated in C/C++? And evaluation order?
Does the ANSI standard mandate logic operators to be short-circuited, in either C or C++? I'm confused for I recall the K&R book saying your code shouldn't depend on these operations being short circuited, for they may not. Could someone please point out where in the standard it's said logic ops are always short-circuited? I'm mostly in...
Short circuit error handling in C
I was wondering if there was a better way of handling the case in C where you want to exit a function as soon as you encounter an error in a series of expressions. (in this case, its a function that returns a NULL on error) e.g. in some C code where they tried to short circuit error handling by combining a series of statements with AND...
Is the SQL WHERE clause short-circuit evaluated?
For example: SELECT * FROM Table t WHERE @key IS NULL OR (@key IS NOT NULL AND @key = t.Key) If @key IS NULL evaluates to true, is @key IS NOT NULL AND @key = t.Key evaluated? If No, why not? If Yes, is it guaranteed? Is it part of ANSI SQL or is it database specific? If database specific, SqlServer? Oracle? MySQL? Reference: S...
I don't like this... Is this cheating the language?
I have seen something like the following a couple times... and I hate it. Is this basically 'cheating' the language? Or.. would you consider this to be 'ok' because the IsNullOrEmpty is evaluated first, all the time? (We could argue whether or not a string should be NULL when it comes out of a function, but that isn't really the questio...
Java short style if evaluation
I can't find the relevant portion of the spec to answer this. In a conditional operator statement in Java, are both the true and false arguments evaluated? So could the following throw a NullPointerException Integer test = null; test != null ? test.intValue() : 0; ...
Explain the following from Accelerated C++ please
I don't understand the following excerpt from Accelerated C++: Starting at Because || is left-associative, and because of the relative precedence of ||,== ,and -, r == 0 || r == rows - 1 || c == 0 || c == cols - 1 means the same as it would if we were to place all of its subexpressions in parentheses: ((r == 0 |...
Do all programming languages have boolean short-circuit evaluation?
In the PHP code if(a() && b()) when the first argument is false, b() will not be evaluated. Similarly, in if (a() || b()) when the first argument is true, b() will not be evaluated.. Is this true for all languages, like Java, C#, etc? This is the test code we used. <?php function a(){ echo 'a'; return false; } function b(){ e...
EXC_BAD_ACCESS on iPhone when using "obj != nil
I've got a very simple line of code in Objective-C: if ((selectedEntity != nil) && [selectedEntity isKindOfClass:[MobileEntity class]]) Occasionally and for no reason I can tell, the game crashes on this line of code with an EXC-BAD-ACCESS. It usually seems to be about the time when something gets removed from the playing field, so I'...
What's the difference between & and && in MATLAB?
What is the difference between the & and && logical operators in MATLAB? ...
Why would a language NOT use Short-circuit evaluation?
Why would a language NOT use Short-circuit evaluation? Are there any benefits of not using it? I see that it could lead to some performances issues... is that true? Why? Related question : Benefits of using short-circuit evaluation ...
What is the difference between Perl's ( or, and ) and ( ||, && ) short-circuit operators?
Which of these subroutines is not like the other? sub or1 { my ($a,$b) = @_; return $a || $b; } sub or2 { my ($a,$b) = @_; $a || $b; } sub or3 { my ($a,$b) = @_; return $a or $b; } sub or4 { my ($a,$b) = @_; $a or $b; } I came to Perl 5 from C and Perl 4 and always used || until I saw more scripts us...
How can this behavior be acomplished? Python "short circuting" test
Hello all, I have the following code: def testGeodatabase(self): geodatabaseList = self.gp.ListWorkspaces("*","ALL") for x in geodatabaseList: if x == self.outputGeodatabase: return True else: pass return False What i need to know the following: in case the if condition evaluates to...
Equivalent to VB AndAlso in SQL?
Is there an equivalent to VB's AndAlso/OrElse and C#'s &&/|| in SQL (SQL Server 2005). I am running a select query similar to the following: SELECT a,b,c,d FROM table1 WHERE (@a IS NULL OR a = @a) AND (@b IS NULL OR b = @b) AND (@c IS NULL OR c = @c) AND (@d IS NULL OR d = @d) For example, if the "@a" parameter passed in as NULL ther...
This is useful but I'm not sure why it works
protected override Boolean IsValid(String propertyValue) { return !String.IsNullOrEmpty(propertyValue) && propertyValue.Trim().Length > 0; } This C# validation method does exactly what I want, but I wasn't aware that you could use expression short-circuiting like this. When propertyValue is null, doesn't execution still need to ev...