Using Approx with the single-include catch2/catch.hpp

[Ben FrantzDale]

We use the old catch and are trying to upgrade to Catch2. I have a file that includes catch just to use its Approx class. However, when using the massive single-include catch.hpp, I see that the definitions of things like Approx::Approx(double) are buried behind #ifdefs. If I #define CATCH_IMPL, then it sees those functions, but then is missing things IReporterFactoryPtr, which is defined above, but hidden by CATCH_CONFIG_EXTERNAL_INTERFACES. If I additionally #define CATCH_CONFIG_EXTERNAL_INTERFACES. Then I need ratio_string, so I #define CATCH_CONFIG_ENABLE_CHRONO_STRINGMAKER... then I have a giant pile of multiple-definitions errors.

Is there a way to use Approx in a header-only way?

[Martin Hořeňovský]

If you include the header, you can just use Approx without any extra defines. You will however, need one TU somewhere with CATCH_CONFIG_IMPL for linking to work properly.

xarn@DESKTOP-B2A3CNC:/mnt/c/ubuntu/temp :) head catch.hpp

/*

 *  Catch v2.7.2

 *  Generated: 2019-04-22 23:13:14.687465

 *  ----------------------------------------------------------

 *  This file has been merged from multiple headers. Please don't edit it directly

 *  Copyright (c) 2019 Two Blue Cubes Ltd. All rights reserved.

 *

 *  Distributed under the Boost Software License, Version 1.0. (See accompanying

 *  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

 */

xarn@DESKTOP-B2A3CNC:/mnt/c/ubuntu/temp :) cat approx.cpp

#include "catch.hpp"

TEST_CASE("Approx") {

    REQUIRE(Approx(1) == 1);

}

xarn@DESKTOP-B2A3CNC:/mnt/c/ubuntu/temp :) clang++ -c approx.cpp -std=c++11

xarn@DESKTOP-B2A3CNC:/mnt/c/ubuntu/temp :)

On Thu, 16 May 2019 at 18:40, Ben FrantzDale <b...@formlabs.com> wrote:

We use the old catch and are trying to upgrade to Catch2. I have a file that includes catch just to use its Approx class. However, when using the massive single-include catch.hpp, I see that the definitions of things like Approx::Approx(double) are buried behind #ifdefs. If I #define CATCH_IMPL, then it sees those functions, but then is missing things IReporterFactoryPtr, which is defined above, but hidden by CATCH_CONFIG_EXTERNAL_INTERFACES. If I additionally #define CATCH_CONFIG_EXTERNAL_INTERFACES. Then I need ratio_string, so I #define CATCH_CONFIG_ENABLE_CHRONO_STRINGMAKER... then I have a giant pile of multiple-definitions errors.

Is there a way to use Approx in a header-only way?

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