96 lines
3.0 KiB
C++
96 lines
3.0 KiB
C++
/* vim: set sw=4 sts=4 et foldmethod=syntax : */
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/** \file
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*
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* Example \ref example_environment.cc "example_environment.cc" .
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*
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* \ingroup g_environment
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*/
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/** \example example_environment.cc
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*
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* This example demonstrates how to use EnvironmentFactory and the resultant
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* Environment.
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*/
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#include <paludis/paludis.hh>
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#include "example_command_line.hh"
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#include <iostream>
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#include <iomanip>
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#include <cstdlib>
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using namespace paludis;
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using namespace examples;
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using std::cout;
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using std::endl;
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using std::left;
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using std::setw;
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int main(int argc, char * argv[])
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{
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int exit_status(0);
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try
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{
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CommandLine::get_instance()->run(argc, argv,
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"example_environment", "EXAMPLE_ENVIRONMENT_OPTIONS", "EXAMPLE_ENVIRONMENT_CMDLINE");
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/* We use EnvironmentFactory to construct an environment from the user's
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* --environment commandline choice. With an empty string, this uses the
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* distribution-defined default environment. With a non-empty string, it
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* is split into two parts upon the first colon (if there is no colon,
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* the second part is considered empty). The first part is the name of
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* the environment class to use (e.g. 'paludis', 'portage') and the
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* second part is passed as parameters to be handled by that
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* environment's constructor. */
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std::shared_ptr<Environment> env(EnvironmentFactory::get_instance()->create(
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CommandLine::get_instance()->a_environment.argument()));
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/* A lot of the Environment members aren't very useful to clients. The
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* mask related methods are used by PackageID, and shouldn't usually be
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* called directly from clients. The system information and mirror
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* functions are mostly for use by Repository subclasses. The []
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* operator is covered in \ref example_selection.cc
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* "example_selection.cc". That leaves the package database and sets.
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* The package database has its own examples, so we'll start with sets:
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* */
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std::shared_ptr<const SetSpecTree> world(env->set(SetName("world")));
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if (world)
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{
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cout << "World set exists" << endl;
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}
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else
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cout << "No world set defined" << endl;
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}
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catch (const Exception & e)
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{
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/* Paludis exceptions can provide a handy human-readable backtrace and
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* an explanation message. Where possible, these should be displayed. */
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cout << endl;
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cout << "Unhandled exception:" << endl
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<< " * " << e.backtrace("\n * ")
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<< e.message() << " (" << e.what() << ")" << endl;
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return EXIT_FAILURE;
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}
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catch (const std::exception & e)
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{
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cout << endl;
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cout << "Unhandled exception:" << endl
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<< " * " << e.what() << endl;
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return EXIT_FAILURE;
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}
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catch (...)
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{
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cout << endl;
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cout << "Unhandled exception:" << endl
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<< " * Unknown exception type. Ouch..." << endl;
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return EXIT_FAILURE;
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}
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return exit_status;
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}
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