Leatherman - a C++ toolkit

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Table of Contents generated with DocToc

• Usage
  • Dependencies
  • As a Standalone Library
    • Building Leatherman
    • Using Leatherman
  • As a Submodule
  • Variables Set by Leatherman
  • CMake Helpers Provided by Leatherman
  • Internationalization (i18n)
    • Helper Functions
    • Enabling i18n
    • Extracting and Translating Text
    • Limitations
    • Debugging
  • Using Logging
  • Using Catch
  • Using Windows
  • Using JsonContainer
  • Using curl
• Extending Leatherman
  • Typical Leatherman Directory Structure
  • Sample Library CMakeLists.txt file
  • Vendoring Other Libraries
• How To Release

Usage

Leatherman can be used in one of two ways: It can be installed as a regular library, and included using the normal CMake find_package syntax, or it can be setup as a submodule. The recommended method is to install Leatherman and use it as a regular system library.

Leatherman is broken up into a number of focused component libraries. Both methods of using Leatherman allow you to control which components are built and used.

Library install locations can be controlled using the LIB_SUFFIX variable, which results in installing libraries to lib${LIB_SUFFIX}.

Dependencies

• Boost, at least version 1.54

As a Standalone Library

The recommended way to use Leatherman is as a library built and installed on your system.

Building Leatherman

Leatherman is built like any other cmake project:

mkdir build
cd build
cmake ..
make
sudo make install

By default, all of the component libraries are built when Leatherman is used standalone. To disable a component, you can set LEATHERMAN_ENABLE_<LIBRARY> to any of CMake's falsy values.

Using Leatherman

Leatherman's make install deploys a standard CMake config file to lib/cmake/leatherman. This allows the normal CMake find_package workflow to be used.

find_package(Leatherman COMPONENTS foo bar baz REQUIRED)

If Leatherman is not installed to a standard system prefix, or on Windows where there is no standard prefix, you can set CMAKE_PREFIX_PATH to the location of Leatherman's install.

As a Submodule

Leatherman can be included as a git submodule and added as a CMake subdirectory. Consider the following:

CMakeLists.txt
lib/
    CMakeLists.txt
vendor/
    leatherman/

In this setup, your CMakeLists.txt would need to contain the following:

...
add_subdirectory(vendor/leatherman)
...

To enable individual Leatherman components, you must set LEATHERMAN_ENABLE_<LIBRARY>. Any libraries not explicitly enabled will not be built or available to the containing project.

...
set(LEATHERMAN_ENABLE_LOCALE TRUE)
add_subdirectory(vendor/leatherman)
...

Variables Set by Leatherman

Leatherman sets two top-level CMake variables:

• LEATHERMAN_INCLUDE_DIRS The include paths of all enabled leatherman libraries
• LEATHERMAN_LIBRARIES The library names of all enabled leatherman libraries, as well as their dependencies.

In addition, each enabled library sets a number of library-specific variables:

• LEATHERMAN_<LIBRARY>_INCLUDE The include directory or directories for the given leatherman library.
• LEATHERMAN_<LIBRARY>_LIB The library name as used by CMake. In the case of header-only leatherman libraries, this will be set to the empty string.
• LEATHERMAN_<LIBRARY>_DEPS Any dependency libraries needed by the given library. This could include other leatherman libraries or 3rd-party libraries found via CMake.
• LEATHERMAN_<LIBRARY>_LIBS The contents of both LEATHERMAN_<LIBRARY>_LIB and LEATHERMAN_<LIBRARY>_DEPS

CMake Helpers Provided by Leatherman

In addition to the C++ library components, Leatherman provides a few CMake helpers. These will be automatically added to your CMAKE_MODULE_PATH when find_package is processed.

• options: Common CMake options for leatherman features. Should almost always be used.

• cflags: Sets a LEATHERMAN_CXX_FLAGS variable containing the Puppet Labs standard CXXFLAGS for your compiler and platform.

• leatherman: Additional functionality provided by Leatherman for consumers. Includes:

  • Helpers for dealing with variables and scopes
  • Debugging macros
  • cpplint and cppcheck configuration
  • Logging configuration
  • Install command with cross-platform defaults
  • Symbol visibility configuration

• pod2man: Adds a pod2man macro to generate man files from source.

Internationalization (i18n)

Leatherman and its components provide support for generating and using gettext-based message catalogs.

Helper Functions

Two helpers are provided for generating message catalogs:

• gettext_templates <dir> <sources>: creates a ${PROJECT_NAME}.pot target (used by all) that (re)generates the .pot file from specified source files. If the project is configured with LEATHERMAN_LOCALES containing a list of language codes, it will add a target ${PROJECT_NAME}-${LANG}.po to create or update translation (.po) files matching those codes. Files are put in dir. To avoid make clean deleting these files, look at how the locales directory is structured.
• gettext_compile <dir> <inst>: creates a translation target (also used by all) to generate the binary message catalogs (.mo files) and configure installing them to the specified install location (inst).

LEATHERMAN_LOCALES expects a quoted semi-colon separated list, as in LEATHERMAN_LOCALES="en;fr;ja".

Normal use of cmake/make should ensure the translation files are up-to- date. Translations can be tested by setting the LC_CTYPE environment variable.

Enabling i18n

By default i18n support is disabled. To enable it, define LEATHERMAN_I18N when compiling your project. To do so, add these two lines to your projects CMakeLists.txt file below where you have find_package(LEATHERMAN ...) and also below where you do include(cflags).

add_definitions(${LEATHERMAN_DEFINITIONS})
add_definitions(-DLEATHERMAN_I18N)

By default locale files are installed to ${CMAKE_INSTALL_PREFIX}/share/locale. This behavior can be changed to use environment variables for the prefix instead by defining LEATHERMAN_LOCALE_VAR and LEATHERMAN_LOCALE_INSTALL. LEATHERMAN_LOCALE_VAR should refer to an environment variable pointing to the root of the Leatherman install, while LEATHERMAN_LOCALE_INSTALL should contain a path relative to that location, where locale files should be installed and searched for at run time.

For example, if Leatherman is installed to C:/tools, and you would like to install translation files to C:/languages/leatherman, you can create an environment variable (e.g. $LEATHERMAN_LOCATION) containing C:\tools, then set LEATHERMAN_LOCALE_VAR=LEATHERMAN_LOCATION and LEATHERMAN_LOCALE_INSTALL=../languages/leatherman. Then locale files will be installed to C:/tools/../languages/leatherman and at runtime Leatherman will search for locale files there.

To ensure that consuming projects also install their locale files to the right location, it is recommended to set LEATHERMAN_LOCALE_INSTALL for all projects attempting to use Leatherman's i18n tooling.

Extracting and Translating Text

The format strings in logging (the first argument) will automatically be extracted for the translation template file and translated. Substitution arguments will not, and must be explicitly translated.

To translate strings outside of logging, use the leatherman::locale::translate and leatherman::locale::format helpers. Strings passed to the helpers will be extracted to .po files. There are several versions of these helpers:

• Basic version (translate, format) for most standard translations.

translate("Apple");

• Pluralized (translate_n, format_n) when translation depends on number of items.

// Note the parameter duplication: The first count value `2` selects the appropriate
// translated message, and the second `2` fills in the `{1}` substitution token.
format_n("{1} Apple", "{1} Apples", 2, 2);

• Prefixed-context (translate_p, format_p) when a word or phrase has multiple meanings.

translate_p("Fruit", "Apple")

• Pluralized and prefixed-context (translate_np, format_np)

format_np("Fruit", "{1} Apple", "{1} Apples", 3, 3);

leatherman::locale::format is a replacement for boost::locale::format, which adds locale-aware formatting to boost::format, but requires different substitution tokens. To support transparently enabling LEATHERMAN_I18N for only some platforms in a project, leatherman::locale::format falls-back to using boost::format, and will convert substitution tokens using the regex {(\d+)} to %\1%. To be safe, assume both formats are special when using format, and use {N} in as the substitution token for your strings. If you need to support both modes and use advanced substitution strings, you'll have to use an #ifdef LEATHERMAN_I18N block to use the correct string.

To use leatherman::locale::translate or leatherman::locale::format in your project, add an include to the top of your cpp file:

#include <leatherman/locale/locale.hpp>

Next, if you would like to use any of the functions, you could do so by following this example:

std::cout << leatherman::locale::translate("This is translated") << std::endl;
std::cout << leatherman::locale::format("This is {1} translated message", 1) << std::endl;

Leatherman also provides format helpers with short names: (), n(), p_(), np_(). These reduce code disruption when adding i18n support, and naming is consistent with macros from other i18n libraries.

using namespace leatherman::locale;
std::cout << _("This is translated") << std::endl;
std::cout << _("This is {1} translated message", 1) << std::endl;

Limitations

Note that on Windows when building Leatherman.Locale as a DLL and Boost.Locale statically, you can get some weird behavior from Boost.Locale. Avoid using it directly, and ensure all translation operations happen as part of the Leatherman.Locale DLL memory space (i.e. in source files).

Translation isn't supported on AIX or Solaris, as GCC on those platforms doesn't support std::locale. In fact std::locale is buggy, so avoid using get_locale as well. The CMake option LEATHERMAN_USE_LOCALES can be used to enable or disable building with Boost.Locale and using std::locale.

Debugging

If output strings are not being translated, gettext's FAQ has some suggestions for debugging.

(maint) Add debugging i18n to README

Using Logging

Each .cc file that uses logging (or includes a header which uses logging) needs to know its logging name