[GiNaC-devel] Mysterious push_front()

[Jan Rheinländer]

Hi Richard,

but when I try to compile this program

#include <ginac/ginac.h>
using namespace GiNaC;

int main(int argc, char** argv)
{
        exprseq seq{1,2,3};
        seq.prepend(0);
        return 0;
}

I get error:

In file included from /usr/include/ginac/lst.h:26,
                 from /usr/include/ginac/normal.h:29,
                 from /usr/include/ginac/ginac.h:31,
                 from test.cpp:24:
/usr/include/ginac/container.h: In instantiation of 
‘GiNaC::container<C>& GiNaC::container< <template-parameter-1-1> 
 >::prepend(const GiNaC::ex&) [with C = std::vector]’:
test.cpp:30:15:   required from here
/usr/include/ginac/container.h:551:12: error: 
‘GiNaC::container_storage<std::vector>::STLT’ {aka ‘class 
std::vector<GiNaC::ex>’} has no member named ‘push_front’
  551 |  this->seq.push_front(b);
      |  ~~~~~~~~~~^~~~~~~~~~

Why not change the code of prepend() in container.h to use insert() 
instead of push_front()? Then I think it will work for all STL containers.

Jan

Am 02.03.22 um 23:44 schrieb Richard B. Kreckel:
> Hi Jan,
>
> On 02.03.22 18:55, Jan Rheinländer wrote:
>> sometimes GiNaCs templates are a mystery to me. In container.h there is
>> the code
>>
>> template<template<classT, class= std::allocator<T>> classC>
>> container<C> & container<C>::prepend(constex & b)
>> {
>>         ensure_if_modifiable();
>>         this->seq.push_front(b);
>>         return*this;
>> }
>>
>> but AFAIK the STL does not have any push_front() method. And GiNaC does
>> not seem to define it either. How can this work?
>>
>> Same applies for pop_front() and sort()
>>
>> voidsort_(std::input_iterator_tag)
>>         {
>>                 this->seq.sort(ex_is_less());
>>         }
> Well, not every STL container provides every possible method.
> But the standard does require the ones you mention for the instantiated
> template classes. Check again!
>
>    -richy.
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