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Re: [paho-dev] Building the C++ API/samples

Hello Ian,

Yes, several people asked me about this, particularly people stuck with an older cross-compiler for an embedded system. Including me, as it turns out! The earliest GCC I suspect that would work is 4.6. For Windows, DevStudio 2012 is needed (though I still have to do more testing on Windows to be sure this works properly).

The implementation makes heavy use of the C++11 libraries - threads, sync objects, time (chrono), and shared pointers. When we discussed this prior to my submission last spring, everyone seemed OK to proceed along these lines as we could "look forward" with the C++ implementation, since people could fall back to the C library if necessary.

I was, however, going to investigate using Boost for older compilers - so Boost would *not* be needed (at all) for a C++11 compiler, but could be used for an older compiler. It has nearly drop-in replacements for threading, time/chrono, and shared pointer libraries. I would still need to change/remove a few of the new language features (nullptr, noexcept, etc).

But without using Boost, the required changes/additions would be a lot of work.

To be clear, we would not need to ship any boost code (no licensing issues), but anyone with GCC <= 4.5 or VisualStudio <= 2010, could still use the Paho C++ library with Boost as an external requirement. And since Boost can be cross-compiled easily enough, this is a viable solution for embedded cross-compiled targets.

What do you think of that?


On 11/13/2013 11:27 AM, Ian Craggs wrote:
Hi Frank,

trying to build the C++ samples on my RedHat workstation, I get the output included below. At least the first one is presumably due to the older version of gcc installed (4.4.7-3) - I haven't looked at the rest yet. But the version of gcc installed on at least one of the Eclipse build servers is older than that (4.3.4).

Should/could we have a solution for pre C++11 compilers?


g++ -I.. -I../../../org.eclipse.paho.mqtt.c/src -D_NDEBUG -Wall -std=c++0x -O2 -o async_publish async_publish.cpp -L../lib -L../../../org.eclipse.paho.mqtt.c/src/linux_ia64 -lmqttpp -lmqttv3a
In file included from ../mqtt/token.h:32,
from ../mqtt/async_client.h:31,
from async_publish.cpp:23:
../mqtt/exception.h:73: error: expected ‘;’ before ‘noexcept’
../mqtt/exception.h:76: error: expected ‘;’ before ‘}’ token
In file included from ../mqtt/async_client.h:31,
from async_publish.cpp:23:
../mqtt/token.h: In member function ‘bool mqtt::token::wait_until_completion(const std::chrono::time_point<_Clock, _Duration1>&)’:
../mqtt/token.h:315: error: expected primary-expression before ‘[’ token
In file included from ../mqtt/async_client.h:35,
from async_publish.cpp:23:
../mqtt/connect_options.h: In constructor ‘mqtt::connect_options::connect_options()’: ../mqtt/connect_options.h:63: error: could not convert ‘{{'M', 'Q', 'T', 'C'}, 2, 60, 1, 10, 0l, 0l, 0l, 30, 20, 0l, 0l, 0, 0l}’ to ‘MQTTAsync_connectOptions’
async_publish.cpp: In function ‘void sleep(int)’:
async_publish.cpp:38: error: ‘sleep_for’ is not a member of ‘std::this_thread’
async_publish.cpp: In function ‘int main(int, char**)’:
async_publish.cpp:143: error: ‘nullptr’ was not declared in this scope

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