Re: error: no matching constructor for initialization of 'string_vector'

[Ben Abbott]

> \On Aug 25, 2016, at 9:01 AM, Carnë Draug <address@hidden> wrote:
> 
> On 25 August 2016 at 13:23, Ben Abbott <address@hidden> wrote:
>>> On Aug 25, 2016, at 07:09, Carnë Draug <address@hidden> wrote:
>>> 
>>>> On 25 August 2016 at 01:27, Ben Abbott <address@hidden> wrote:
>>>> Carne,
>>>> 
>>>> The chagneset below is giving me an error.
>>>> 
>>>>       http://hg.savannah.gnu.org/hgweb/octave/rev/f38e81248556
>>>> 
>>>> libinterp/octave-value/ov-classdef.cc:2275:17: error: no matching 
>>>> constructor for initialization of 'string_vector'
>>>> string_vector v (names);
>>>>               ^  ~~~~~
>>>> 
>>>> I’m using Apple’s llvm/clang
>>>> 
>>>> Apple LLVM version 7.3.0 (clang-703.0.31)
>>>> 
>>>> Ben
>>> 
>>> I have no idea why your compiler is failing to find the constructor.
>>> Is it because it can't decide which constructor to use?  Which ones
>>> is it undecided about?
>>> 
>>> Carnë
>> 
>> I'm embarrassed to say that I don't know what a constructor is. I'll do a 
>> quick study.
>> 
>> Can give me some background on what your patch is doing?
>> 
> 
> A constructor is a class method that constructs an object of that class.
> The name of those methods is the same as the class name.
> 
> For example, in Octave, these are constructors:
> 
>  p = inputParser (); # construct inputParser object
>  a = audiorecorder (fs, nbits, nchannels); # construct audiorecorder object
> 
> The change I made replaced the code that was manually constructing
> a string_vector, with a string_vector constructor that does the same
> thing.
> 
> In languages like C++, a class can have more than one constructor, even
> with same number of arguments.  The compiler looks at the type of the
> arguments and picks the constructor that fits the best.  Sometimes there's
> more than one constructor that fits, hence my question about what
> constructors is clang considering (gcc error messages mention the
> different possibilities so I'm expcting clang to do something similar).
> 
> In the case of the string_vector class, these are the constructors available:
> 
>    string_vector (void)
> 
>    string_vector (octave_idx_type n)
> 
>    string_vector (const char *s)
> 
>    string_vector (const std::string &s)
> 
>    string_vector (const string_vector &s)
> 
>    template <template <typename...> class String_Container>
>    string_vector (const String_Container<std::string> &lst)
> 
>    string_vector (const Array<std::string> &s)
> 
>    string_vector (const char *const *s)
> 
>    string_vector (const char *const *s, octave_idx_type n)
> 
> In the change that's causing issues for clang, the argument is a
> std::set<std::string> so I would expect it to use the templated
> constructor for String_Container<std::string>.

If I’m following … might clang require an explicit constructor for 
std::set<std::string>?

Ben