variadic-functions

问题 I have two functions check if String/Strings are blank. fun isBlank(s: String?) : Boolean { return s.isNullOrBlank() } fun isBlank(vararg strings: String) : Boolean { return strings.isEmpty() || strings.any { isBlank(it) } } So I try to call first function from the second one but seems it tries to call itself. For instance it works nice in java: public static boolean isBlank(final String string) { return string == null || string.trim().isEmpty(); } public static boolean isBlank(final String..

问题 I have two functions check if String/Strings are blank. fun isBlank(s: String?) : Boolean { return s.isNullOrBlank() } fun isBlank(vararg strings: String) : Boolean { return strings.isEmpty() || strings.any { isBlank(it) } } So I try to call first function from the second one but seems it tries to call itself. For instance it works nice in java: public static boolean isBlank(final String string) { return string == null || string.trim().isEmpty(); } public static boolean isBlank(final String..

问题 Recently I wanted to implement a printf wrapper. After some search I found the vprintf is good for this need: void my_printf(const char *fmt, ...) { va_list args; va_start(args, fmt); vprintf(fmt, args); va_end(args); } But is it possible to implement such a wrapper for printf or any other similar functions with variable arguments instead of va_list ? (I mean, what if they don't provide a v version?) Since some commenter didn't fully capture my idea, I'd better elaborate it. Suppose you have

问题 I try to make a generic, but still efficient multi dimension Point class. What I have is a Dimensions enum enum Dimension : std::size_t { _2D = 2, _3D = 3 }; And a Point class template <typename T, Dimension D> class Point : public std::array<T, D> { public: T& at(size_t idx) { return std::array<T,D>::at(idx); }; const T& at(size_t idx) const { return std::array<T,D>::at(idx); }; Dimension dim() const { return D; } ... }; I would like to create nices constructors so I added (outside my class

问题 Please, could you help me to understand why compilation of first call of testVargArgsAutoboxingPriority fails? In case of second call compiler is able to select proper method by preferring primitive (first parameter) to Object but after varargs parameter addition compiler is not able to make the selection any more. Fail message is \jdk1.6.0_45\bin\javac.exe ocjp6/AutoBoxingOldStyleVarargsPriority.java ocjp6\AutoBoxingOldStyleVarargsPriority.java:7: reference to testVargArgsAutoboxingPriority

问题 I'm looking for a way, given a function's signature, to canonicalize it's args and kwargs. That is, any kwargs passed in already in the signature of the function should be converted to args. For example: def myfunc(a, b=0, c=0, **kwargs): pass def canonicalize(func, *args, **kwargs): something = inspect.signature(func) # Do something with args/kwargs here return new_args, new_kwargs Example output: >>> canonicalize(myfunc, 1, 2, g=3) (1, 2), {'g': 3} >>> canonicalize(myfunc, 1) (1,), {} >>>

问题 In a C++/CLI assembly, I'm trying to call a managed delegate from a native callback. I followed Doc Brown's answer here, and my implementation so far looks like this: The native callback - ignore the commented out parts for now: static ssize_t idaapi idb_callback(void* user_data, int notification_code, va_list va) { switch (notification_code) { case idb_event::byte_patched: { //ea_t address = va_arg(va, ea_t); //uint32 old_value = va_arg(va, uint32); return IdaEvents::BytePatched(0, 0); }

问题 I'm trying to develop a function that contains multiple arguments. To be as robust as possible, I want to be able to call my function as follows: foo( x, y, z, 'OptionalArg1', bar, 'OptionalArg2', blah, 'OptionalArg3', val ) I want my function to be robust enough to contain any combination of these arguments in any order. I also need to be able to set defaults if the argument is not provided. Is there a standard way to do this in MATLAB? 回答1: The best way would be to use the inputParser class

问题 I'm trying to do something similar to C++11 variable number of arguments, same specific type, but I have my own type: struct Foo { Foo(int) {} Foo(int, int) {} }; with a bunch of overloads void f() {} void f(const Foo&) {} void f(const Foo&, const Foo&) {} // etc. ... as many f() overloads as needed ... works as desired: f(); f(1); f(1, 2); f(1, { 2, 3 }); . Instead of overloads, I can also use std::initializer_list<> with the {} syntax (as suggested here): void g_(std::initializer_list<Foo>)

问题 I know that declaring a function (or function pointer) with no parameter list (and without specifying void in the parameter list) that means that the function (or function pointer) has an unknown number of arguments. I wrote some test scripts to check this behavior out: int my_func_1() { return(0); } int my_func_2(int x) { return(x); } int my_func_3(char x, ...) { va_list va; va_start(va, x); return(va_arg(va, int)); } int (*fp)(); fp = my_func_1; printf("%d\n", fp()); fp = my_func_2; printf(