Tutorial by Examples: er

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This is an enum that is also a callable function that tests String inputs against precompiled regular expression patterns. import java.util.function.Predicate; import java.util.regex.Pattern; enum RegEx implements Predicate<String> { UPPER("[A-Z]+"), LOWER("[a-z]+&quot...

You can overload all basic arithmetic operators: + and += - and -= * and *= / and /= & and &= | and |= ^ and ^= >> and >>= << and <<= Overloading for all operators is the same. Scroll down for explanation Overloading outside of class/struct: //operator...

You can overload the 2 unary operators: ++foo and foo++ --foo and foo-- Overloading is the same for both types (++ and --). Scroll down for explanation Overloading outside of class/struct: //Prefix operator ++foo T& operator++(T& lhs) { //Perform addition return lhs; } ...

You can overload all comparison operators: == and != > and < >= and <= The recommended way to overload all those operators is by implementing only 2 operators (== and <) and then using those to define the rest. Scroll down for explanation Overloading outside of class/struct: ...

You can overload type operators, so that your type can be implicitly converted into the specified type. The conversion operator must be defined in a class/struct: operator T() const { /* return something */ } Note: the operator is const to allow const objects to be converted. Example: struct ...

You can even overload the array subscript operator []. You should always (99.98% of the time) implement 2 versions, a const and a not-const version, because if the object is const, it should not be able to modify the object returned by []. The arguments are passed by const& instead of by value...

You can overload the function call operator (): Overloading must be done inside of a class/struct: //R -> Return type //Types -> any different type R operator()(Type name, Type2 name2, ...) { //Do something //return something } //Use it like this (R is return type, a and b a...

The assignment operator is one of the most important operators because it allows you to change the status of a variable. If you do not overload the assigment operator for your class/struct, it is automatically generated by the compiler: the automatically-generated assignment operator performs a &qu...

Overloading the bitwise NOT (~) is fairly simple. Scroll down for explanation Overloading outside of class/struct: T operator~(T lhs) { //Do operation return lhs; } Overloading inside of class/struct: T operator~() { T t(*this); //Do operation return t; } Note...

The operators << and >> are commonly used as "write" and "read" operators: std::ostream overloads << to write variables to the underlying stream (example: std::cout) std::istream overloads >> to read from the underlying stream to a variable (example: s...

Bosun alerts are defined in the config file using a custom DSL. They use functions to evaluate time series data and will generate alerts when the warn or crit expressions are non-zero. Alerts use templates to include additional information in the notifications, which are usually an email message and...

This method can be used to convert a formatted string representation of a date into a Date object. /** * Parses the date using the given format. * * @param formattedDate the formatted date string * @param dateFormat the date format which was used to create the string. ...

An assertion is a statement used to assert that a fact must be true when that line of code is reached. Assertions are useful for ensuring that expected conditions are met. When the condition passed to an assertion is true, there is no action. The behavior on false conditions depends on compiler fl...

C11 Static assertions are used to check if a condition is true when the code is compiled. If it isn't, the compiler is required to issue an error message and stop the compiling process. A static assertion is one that is checked at compile time, not run time. The condition must be a constant expres...

lscount returns a time bucketed count of matching documents in the LogStash index, according to the specified filter. A trivial use of this would be to check how many documents in total have been received in the 5 minutes, and alert if it is below a certain threshold. A Bosun alert for this might ...

lsstat returns various summary stats per bucket for the specified field. The field must be numeric in elastic. rStat can be one of avg, min, max, sum, sum_of_squares, variance, std_deviation. The rest of the fields behave the same as lscount, except that there is no division based on bucketDuratio...

#include <stdio.h> #define is_const_int(x) _Generic((&x), \ const int *: "a const int", \ int *: "a non-const int", \ default: "of other type") int main(void) { const int i = 1; int j = 1; double...

#include <stdio.h> void print_int(int x) { printf("int: %d\n", x); } void print_dbl(double x) { printf("double: %g\n", x); } void print_default() { puts("unknown argument"); } #define print(X) _Generic((X), \ int: print_int, \ double: pri...

For lambdas with a single return statement, or multiple return statements whose expressions are of the same type, the compiler can deduce the return type: // Returns bool, because "value > 10" is a comparison which yields a Boolean result auto l = [](int value) { return value &gt...