TL;DR Python reads the expression as [0xf or (x in (1, 2, 3))], because: The Python tokenizer. Operator precedence. It never raises NameError thanks to short-circuit evaluation – if the expression left to the or operator is a truthy value, Python will never try to evaluate the right side of it. Parsing hexadecimal numbers First, … Read more
Yes, it will be short-circuited. Your code is equivalent to: bool first = await first_check(); if (first) { bool second = await second_check(); if (second) { … } } Note how it won’t even call second_check until the awaitable returned by first_check has completed. So note that this won’t execute the two checks in parallel. … Read more
This is a trick question. b is an input argument to the sc_and method, and so will always be evaluated. In other-words sc_and(a(), b()) will call a() and call b() (order not guaranteed), then call sc_and with the results of a(), b() which passes to a?b:0. It has nothing to do with the ternary operator … Read more
First of all, thanks for pointing out that the spec isn’t clear on the non-dynamic nullable-bool case. I will fix that in a future version. The compiler’s behavior is the intended behavior; && and || are not supposed to work on nullable bools. The dynamic binder does not seem to implement this restriction, though. Instead, … Read more
Yes, the PHP interpreter is “lazy”, meaning it will do the minimum number of comparisons possible to evaluate conditions. If you want to verify that, try this: function saySomething() { echo ‘hi!’; return true; } if (false && saySomething()) { echo ‘statement evaluated to true’; }
Reason The operators &&= and ||= are not available on Java because for most of the developers these operators are: error-prone useless Example for &&= If Java allowed &&= operator, then that code: bool isOk = true; //becomes false when at least a function returns false isOK &&= f1(); isOK &&= f2(); //we may expect … Read more
One natural solution would look like this: bool b1 = SomeCondition(); bool b2 = b1 || SomeOtherCondition(); bool b3 = b2 || SomeThirdCondition(); // any other condition bool bn = bn_1 || SomeFinalCondition(); if (bn) { // do stuff } This has the benefits of being easy to understand, being applicable to all cases and … Read more
Twig example: {% if array.key is defined %} // do something {% else %} // do something else {% endif %}
The single ampersand & is the logical AND operator. The double ampersand && is again a logical AND operator that employs short-circuiting behaviour. Short-circuiting just means the second operand (right hand side) is evaluated only when the result is not fully determined by the first operand (left hand side) A & B (A and B … Read more
From the Java 6 JLS: At run time, the first operand expression of the conditional expression is evaluated first; if necessary, unboxing conversion is performed on the result; the resulting boolean value is then used to choose either the second or the third operand expression: If the value of the first operand is true, then … Read more