Macros are a text substitution mechanism. Templates are a functional turing-complete language that is executed at compile time and is integrated into the C++ type system. You can think of them as a plugin mechanism for the language.
The trick is that kwargs has to be accessed at least once in any macro that should accept them. That is to say, you must call {{ kwargs }} once in macro body without declaring it in macro argument list. The same is true for {{ varargs }}. This will not work {% macro example_2(one, … Read more
I think the best way to document these is with example code, as Miles has been doing in his experimental macro based branch of shapeless.
I am pretty sure that it is a bad practice to add another include guard like: #ifndef __HEADER_A_HPP__ #include “header_a.hpp” #endif Here are some reasons why: To avoid double inclusion it is enough to add a usual include guard inside the header file itself. It does the job well. Another include guard in the place … Read more
Linux kernel uses a nice implementation of ARRAY_SIZE to deal with this issue: #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr)) with #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) and #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) Of course this is portable only in GNU C as it makes use of two instrinsics: typeof operator and __builtin_types_compatible_p function. Also it uses … Read more
At the moment, some #defines are converted and some aren’t. More specifically: #define A 1 …becomes: var A: CInt { get } Or: #define B @”b” …becomes: var B: String { get } Unfortunately, YES and NO aren’t recognized and converted on the fly by the Swift compiler. I suggest you convert your #defines to … Read more
Macros don’t directly expand recursively, but there are workarounds. When the preprocessor scans and expands pr(5): pr(5) ^ it creates a disabling context, so that when it sees pr again: ((5==1)? 1 : pr(5-1)) ^ it becomes painted blue, and can no longer expand, no matter what we try. But we can prevent our macro … Read more
No, C# does not support preprocessor macros like C. Visual Studio on the other hand has snippets. Visual Studio’s snippets are a feature of the IDE and are expanded in the editor rather than replaced in the code on compilation by a preprocessor.
It allows tools like sparse to tell kernel developers that they’re possibly using an untrusted pointer (or a pointer that may be invalid in the current virtual address mapping) improperly.
Macro expansion is a complex process that is really only understandable by understanding the steps that occur. When a macro with arguments is recognized (macro name token followed by ( token), the following tokens up to the matching ) are scanned and split (on , tokens). No macro expansion happens while this is happening (so … Read more