environment.hpp

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/** ************************************************************************************************
 * \file
 * This header file is part of sub-namespace #  alib::lang::system of module \alib_basecamp of
 * the \aliblong.
 *
 * \emoji :copyright: 2013-2024 A-Worx GmbH, Germany.
 * Published under \ref mainpage_license "Boost Software License".
 **************************************************************************************************/
#ifndef HPP_ALIB_CAMP_ENVIRONMENT
#define HPP_ALIB_CAMP_ENVIRONMENT 1
 
#if !defined (HPP_ALIB_STRINGS_ASTRING)
#   include "alib/strings/astring.hpp"
#endif
 
ALIB_ASSERT_MODULE(CAMP)
 
#if !defined (HPP_ALIB_STRINGS_CSTRING)
#   include "alib/strings/cstring.hpp"
#endif
 
namespace alib { namespace  lang::system {
 
/** ************************************************************************************************
 * Simple struct providing one static method that reads an environment variable into an
 * \alib string type.
 *
 * While under posix compatible operating systems, environment variable names are
 * case sensitive, under Microsoft windows they are not.
 **************************************************************************************************/
struct EnvironmentVariables
{
    /** ************************************************************************************************
     * Reads an environment variable into an \alib string.
     *
     * \attention
     *    1. While under posix compatible operating systems, environment variable names are
     *       case sensitive, under Microsoft windows they are not.
     * \attention
     *    2. As documented with
     *    \https{std::getenv,en.cppreference.com/w/cpp/utility/program/getenv}, the operation is
     *    not thread safe against changes of the environment in parallel threads.
     *
     *  @param varName      The name of the variable to be retrieved.
     *  @param target       An AString to write the result to.
     *  @param targetData   If \c CurrentData::Keep, the parameter \p{target} is not cleared
     *                      before the result is written. Defaults to \c CurrentData::Clear.
     *  @return \c true if variable was found.
     **************************************************************************************************/
    ALIB_API static
    bool  Get(  const CString&    varName,
                AString&          target,
                lang::CurrentData targetData  =lang::CurrentData::Clear  );
};
 
} // namespace alib[:: lang::system]
 
/// Type alias in namespace \b alib.
using     EnvironmentVariables=        lang::system::EnvironmentVariables;
 
}  // namespace [alib]
 
#endif // HPP_ALIB_CAMP_ENVIRONMENT