Where is boostvariant.hpp

However, the new value may have a different type from the old value. The only requirement is that the types must have been passed as template parameters to boost::variant so they are known to the boost::variant variable.

Now a union can contain a std::string. Because boost::variant is a template, at least one parameter must be specified. One or more template parameters specify the supported types. In Example However, if you tried to assign a value of type int to v , the resulting code would not compile. To display the stored values of v , use the free-standing function boost::get see Example Specifying an invalid type will result in a run-time error because validation of types does not take place at compile time.

Variables of type boost::variant can be written to streams such as the standard output stream, bypassing the hazard of run-time errors see Example For type-safe access, Boost. This class must overload operator for every type used by the boost::variant variable it acts on. That beats using magic. Yeah, I could send a PR to Spirit devs. I'm pretty sure they'd be interested in refactoring a bit before landing, because the whole thing was largely copy-paste.

Show 4 more comments. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta.

Now live: A fully responsive profile. Linked 2. Related 2. Hot Network Questions. That is, you don't spell std::cout. These namespaces could be, e. In addition to these namespaces, also the namespaces of template arguments are considered, and these are:.

On top of that, ADL considers associated classes for arguments that are instantiations of class templates, and here these are:. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 1 year, 5 months ago. Active 1 year, 5 months ago. Viewed times. I am experimenting with boost::variant and printing with standard types like the below, works.