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Overview

Artifact ID: 78d143bb9b8be81ca5373a58fbca728a5e97c070e7d9f848e8a08963858d2ead
Page Name:Extras
Date: 2019-01-06 21:01:16
Original User: luismachuca
Parent: d4f085ae2e3f0392a69bab4e4072e4405af88f58c8847e6782e6f4a497869e3d
Content

Besides the normal features that are activated automatically upon inclusion of the library, as well as the Supplements, there are a number of side-projects that don't count as part of cxxomfort's distribution proper. They are being developed separately and rather than integrate with cxxomfort tightly they just depend on the library as a whole.

The idea is to pick a number of features, proposals or general C++ concepts and implement them separately. There are a number of reasons to tackle these features separately:

  • the syntax to implement them is too different to C++'s normal syntax (heavy macros, etc) or is too heavy.
  • the feature is more advanced or convoluted and benefits from being decoupled from most cxxomfort internals.
  • the feature is heavily compiler-dependent.
  • the feature is not standardized yet and/or present only as a proposal.

In order to use these features, they can be cloned or downloaded from their specific repositories.

Last update of this listing: November 2018

List of Extras

  • cxxo-literal_affixes - An emulation of C++11's suffix user-defined literals, that also work as normal function objects.
  • cxxo-vocabulary17 - An external component for the library that adds support for std::optional, std::variant and std::any, the new "vocabulary types" added in C++17.
  • cxxo-static_storage - A storage for types that makes them act as "literal" types like ints: objects are never destructed during the program's lifetime, and references/handles to them are passed around instead.
  • cxxo-auto - Backporting auto in a limited manner.
  • cxxo-udl - An implementation of suffix user-defined literals, simpler than the one above.
  • cxxo-minrange - A minimalistic std::range proposal built around n3350 "A minimal std::range".
  • cxxo-tuple_io - Stream output operators for std::tuple .

Descriptions

Auto/Decltype Emulation

Header: cxxomfort/extras/auto.hpp .
Macro: if enabled, CXXOMFORT_USING_auto is defined.

This header adds the following macros:

CXXO_AUTO( variablename, expr )
CXXO_DECLTYPE( expr )

The above macros allow for emulation of C++11's new "auto" and "decltype" semantics if the compiler supports an equivalent semantic such as typeof in C++03 mode (as GCC's __typeof__). Usage is very simple:

typdef std::list<short> SHL_t; // short-list type
SHL_t shl;
...
CXXO_AUTO (M, shl.size() );
// M is automatically declared as eg.: an unsigned int in this case
...
cout<< M<< endl;

In C++11, the macros extend simply to auto variablename = expr and decltype(expr) respectively.

In C++03, the macros extend to a compiler-supported "typeof" invocation; if none is available, compilation fails with an error messaage of "typeof not supported".

Requirements:

  • In non-C++11 mode, the compiler must support a keyword like __typeof__.

Known Limitations:

  • This feature works in Microsoft C++ ≥ 8.0 thanks to a combination of documented hacks for typeof emulation; however, in this case it can not be used in all the contexts a normal __typeof__ can, so use with caution.
  • When in C++03 mode, remember "typeof" intrinsics may not resolve reference types the same way C++11's decltype does.

»Possible Future Features

I'm considering adding some features that are either from C++11 or from current proposals for TR2 / C++2x and that are easy enough and useful enough to have them implemented in this library. No more details at the moment though.

In consideration at the moment of this writing:

  • default-value-initialized wrapper (from Boost).
  • "degenerate" (primitive type + singular term) proposal.
  • begin/end for typesafe enumeration types.
  • Fixed-time calculation versions for equal, mismatch and the find_* family of algorithms.