pragma

In my django project, I use mysql db for production, and sqlite for tests. Problem is, some of my code rely on model integrity checking. It works well with mysql, but integrity errors are not thrown when the same code is executed in tests. I know that foreign keys checking must be activated in sqlite : PRAGMA foreign_keys = 1; However, I don't know where is the best way to do this activation ( same question here ). Moreover, the following code won't work : def test_method(self): from django.db import connection cursor = connection.cursor() cursor.execute('PRAGMA foreign_keys = ON') c = cursor

I am using #pragma once in my .cpp s and .hpp s and because of that I get a warning for each file that uses it. I have not found any option to disable this kind of warning, only the thing of #ifndef MY_FILE_H #define MY_FILE_H /*...*/ #endif . So would you recommend me to replace each #pragma once with ifndef s? in header: #define MYFILE_H // all the header and in the other files: #ifndef MYFILE_H #include "myfile.hpp" #endif // the rest of the file What do you think, is it better to use it like this? Or there is an option to disable the #pragma once warnings in GCC, that I do not know?

I want to use #pragma (in Xcode) to suppress the warning: warning: instance method '-someMethod' not found (return type defaults to 'id') I've tried: #pragma GCC diagnostic ignored "-Wmissing-declarations" And several others, but nothing works. What warning causes the "instance method not found"? Edit As requested here is the actual code: ... if (sampleRate > 0 && ![self isFinishing]) //<--- Warning here { return self.progress; } ... And the build log output: /Users/User1/Documents/Project/branch/client/Folder/CodeFile.m:26:32:{26:32-26:50}: warning: instance method '-isFinishing' not found

I am trying to check the user_version of the sqlite DB. I have an admin tool to bump the version, but I don't understand the syntax of the pragma statement. I am expecting to test the value in an if-statement. Can someone provide a code sample? When I embed the pragma statement in my objective-c code, the compiler throws an error. I figured it out with the inspiration from newtover, digging into FMDB and re-reading the sqlite3 documentation (it is still very vague in my opinion). This code returns the value that I bumped in the admin tool when I make notable changes to the schema that require

Is there a difference between the two examples below for beginning a Perl script? If so, when would I use one over the other? example 1: #!/usr/bin/perl use warnings; example 2: #!/usr/bin/perl -w Using the switch will enable all warnings in all modules used by your program. Using the pragma you enable it only in that specific module (or script). Ideally, you use warnings in all your modules, but often that's not the case. Using the switch can get you a lot of warnings when you use a third party module that isn't warnings-safe. So, ideally it doesn't matter, but pragmatically it's often

I've started a new project and have decided to make sure it builds cleanly with the /Wall option enabled. The only problem is not all 3rd party libraries (like boost) compile without warnings, so I've resorted to doing this in a shared header: #pragma warning(push) #pragma warning(disable:4820) #pragma warning(disable:4619) #pragma warning(disable:4668) #pragma warning(disable:4625) #pragma warning(disable:4626) #pragma warning(disable:4571) #pragma warning(disable:4347) #pragma warning(disable:4640) #pragma warning(disable:4365) #pragma warning(disable:4710) #pragma warning(disable:4820)

What's the point of telling the compiler specifically to include the file only once? Wouldn't it make sense by default? Is there even any reason to include a single file multiple times? Why not just assume it? Is it to do with specific hardware? There are multiple related questions here: Why is #pragma once not automatically enforced? Because there are situations in which you want to include files more than once. Why would you want to include a file multiple times? Several reasons have been given in other answers (Boost.Preprocessor, X-Macros, including data files). I would like to add a

There appears to be a new pragma named parent that does roughly the same thing as base . What does parent do that warrants a new (non-core) module? I am missing something? ysth base tried to do one too many things – automatically handling loading modules but also allowing establishing inheritance from classes already loaded (possibly from a file whose name wasn't based on the module name). To sort of make it work, there was some hackery that caused surprising results in some cases. Rather than break backwards compatibility, a new, replacement pragma parent was introduced with cleaner semantics