What is wrong with my template gJoin() function?

Szyk Cech

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Jul 6, 2019, 11:54:28 AM7/6/19

to

Hi
I want to write nice join template function. In order to work with
different containers and with wide and narrow strings it must be template.
Now I have some thing like this:

/**
* @brief Joins strings in container.
* @param aStringList an container wiht strings.
* @param aDelimiter string witch joins strings in container.
* @result String joined with delimiter.
*/

template<template<typename> typename tContainer, typename tString>
tString gJoin(const tContainer<tString>& aStringList, const tString&
aDelimiter)
{
tString lResult;
for(tString lPart : aStringList)
{
if(lResult.size() > 0)
lResult += aDelimiter;
lResult += lPart;
}

return lResult;
}

But it not works. My g++ is:
gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)

I learn that it should work from:
https://en.cppreference.com/w/cpp/language/template_parameters

Error is like this:

/home/szyk/!-EnergoKod/!-Libs/EnergoKodTools2/Tests/Src/StringTest.cpp:
In member function ‘void StringTest::test7()’:
/home/szyk/!-EnergoKod/!-Libs/EnergoKodTools2/Tests/Src/StringTest.cpp:126:76:
error: no matching function for call to
‘gJoin<std::vector<std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >,
std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > > >,
std::__cxx11::string>(std::vector<std::__cxx11::basic_string<char> >&,
std::__cxx11::basic_string<char>)’
std::string lTest1A(gJoin<vector<string>, string>(lVector1,
string(" ")));

^
In file included from
/home/szyk/!-EnergoKod/!-Libs/EnergoKodTools2/Tests/Src/StringTest.cpp:4:0:
/home/szyk/!-EnergoKod/!-Libs/EnergoKodTools2/Include/EnergoKodTools2/Strings.h:148:9:
note: candidate: template<template<class> class tContainer, class
tString> tString ekt2::gJoin(const tContainer<tString>&, const tString&)
tString gJoin(const tContainer<tString>& aStringList, const tString&
aDelimiter)
^~~~~
/home/szyk/!-EnergoKod/!-Libs/EnergoKodTools2/Include/EnergoKodTools2/Strings.h:148:9:
note: template argument deduction/substitution failed:
Tests/CMakeFiles/EnergoKodTools2Test.dir/build.make:158: recipe for
target 'Tests/CMakeFiles/EnergoKodTools2Test.dir/Src/StringTest.cpp.o'
failed
make[2]: ***
[Tests/CMakeFiles/EnergoKodTools2Test.dir/Src/StringTest.cpp.o] Error 1
make[1]: *** [Tests/CMakeFiles/EnergoKodTools2Test.dir/all] Error 2
make: *** [all] Error 2
CMakeFiles/Makefile2:122: recipe for target
'Tests/CMakeFiles/EnergoKodTools2Test.dir/all' failed
Makefile:129: recipe for target 'all' failed
17:45:51: Proces "/usr/bin/cmake" zakończył się kodem wyjściowym 2.
Błąd budowania / instalowania projektu EnergoKodTools2 (zestaw narzędzi:
Desktop Qt 5.12.3 GCC 64bit2)
Podczas wykonywania kroku "Wersja CMake"

please help me,
best regards,
and thanks in advance
Szyk Cech

Szyk Cech

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Jul 6, 2019, 2:00:02 PM7/6/19

to

Thanks a lot!!!

I improve my code with your help! And it pass all my tests now.

Problem was that I rely on Qt Creator buildin C++ parser (based on CLang
compiler libraries). And how ever I have compile able and valid template
function code, I try crazy calls of this function, because I believe in
parser. Apparently it does not recognize C++17 fully. Not sure, but
maybe it is not upgraded to newest version (but I have newest Qt Creator).

Final version of my gJoin() template function looks like:

/**
* @brief Joins wide and narrow strings in any container.
* @param aStringList an container with strings.

* @param aDelimiter string witch joins strings in container.
* @result String joined with delimiter.

* @warning Don't call this function with different string types
* as containter template parameter and as delimiter - if you do this
you will
* get compile error.

*/

template<template<typename> typename tContainer, typename tString>
tString gJoin(const tContainer<tString>& aStringList, const tString&
aDelimiter)
{
tString lResult;

for(tString lPart : aStringList)
{

if(not lResult.empty())

Heinz Müller

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Jul 14, 2019, 5:16:38 AM7/14/19

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Your code is wonderful! Everyone should code like that!

Christian Gollwitzer

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Jul 15, 2019, 1:41:43 AM7/15/19

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Am 14.07.19 um 11:16 schrieb Heinz Müller:

> Your code is wonderful! Everyone should code like that!

ROFL

G G

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Jul 15, 2019, 9:23:01 AM7/15/19

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-----------------------------

template < typename tContainer, typename tString >
tString gJoin( const tContainer &aStringList, const tString &aDelimiter )