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- Dictionarydefer/dɪˈfəː/
verb
- 1. put off (an action or event) to a later time; postpone: "they deferred the decision until February"
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Sep 7, 2015 · This implementation is zero-overhead unlike some other answers, as well as syntactically nicer and easier to use. It also has zero dependencies, reducing compile times. You can paste this snippet anywhere in your codebase and it will just work. #ifndef defer. struct defer_dummy {}; template <class F> struct deferrer { F f; ~deferrer() { f(); } };
Apr 30, 2015 · 1. Note that on step 4, the preprocessor doesn't look backward: if say you have a macro that expands to () it doesn't look back to see if there was a macro name preceding this invocation. That's what makes DEFER work. Step #1 (fully replace each argument in isolation) makes EXPAND work. – Igor Tandetnik.
Jul 1, 2023 · char* c = log_malloc(30); DEFER(log_free, c); POST_DEFER(); test(); return 0; This code works and, in my basic benchmarking compared to just manually ordering the destructor statements, has about a 10% performance overhead. However, it is limited in the number of DEFER macro calls that can be handled.
1. C does not have destructors (unless you think of the GCC specific variable attribute cleanup, which is weird and rarely used; notice also that the GCC function attribute destructor is not what other languages, C++ notably, call destructor). C++ have them. And C & C++ are very different languages.
Mar 17, 2021 · Both use same technique and use an object to do the RAII. so the macro (#define) is to declare an "unique" identifier (of the type of their object) to be able to call defer several time in the same function, so after MACRO replacement, it result to something like:
162. The real answer is: Because you cannot trust defer. In concept, defer and async differ as follows: async allows the script to be downloaded in the background without blocking. Then, the moment it finishes downloading, rendering is blocked and that script executes. Render resumes when the script has executed.
Sep 26, 2021 · In this Modern C video there's a trick that allows to postpone execution of a code until the block/scope exits. It's used as follows: int main() { int foo=0, bar; const char *etc = "Some
May 9, 2018 · 153. If you want to implement a while loop, you will need to use recursion in the preprocessor. The easiest way to do recursion is to use a deferred expression. A deferred expression is an expression that requires more scans to fully expand: #define EMPTY()
Mar 17, 2009 · Jul 3, 2013 at 22:38. 1. If you invoke the macro more than once, you need each typedef to be unique. If __COUNTER__ is not available, the failover is to use __LINE__, but that will fail of you have the bad luck of using the macro on the same line in two different source files. – EBlake.
Dec 25, 2018 · A "defer" statement invokes a function whose execution is deferred to the moment the surrounding function returns. Each time a "defer" statement executes, the function value and parameters to the call are evaluated as usual and saved anew but the actual function is not invoked. Instead, deferred functions are invoked immediately before the ...
