std::ofstream of;

of.open( path.c_str(),

append ? std::ios_base::app : std::ios_base::trunc

);

if (of){

return of;

}

throw std::runtime_error(

"Could not write to file \"" + path.string() + "\"!"

);

const std::string& line,

const fs::path& path,

bool append = false

){

std::ofstream of { getFile(path, append) };

of << line << '\n';

of.close();

fs::path m_path;

bool m_append {false};

LineWriter(const fs::path& p) : m_path {p} {}

void append(bool b){ m_append = b; }

void write( const std::string& str ){

writeLine(str, m_path, m_append);

}

const fs::path wd { fs::current_path().lexically_normal() };

double xmin {0}, xmax {5}, xstep {0.1};

int sleep_ms {100};

using Func = double (*)(double);

Func fn { std::sin };

std::string outf { "outf.dat" };

fs::path outp { wd / outf };

LineWriter lw {outp};

lw.write("title_x title_y");

lw.append(true);

std::stringstream plotCommand; plotCommand

<< "plot "

<< '\"' << outf << '\"' // file

<< " using 1:2" // cols

<< " with lines" // style

;

std::stringstream rng; rng

<< "set xrange [" << xmin << ':' << xmax << ']';

GnuplotPipe gp;

gp.open();

gp.sendLine( "cd \"" + wd.string() + "\"" );

gp.sendLine( "set key autotitle columnhead" );

gp.sendLine( rng.str() );

bool first {true};

for ( double x{xmin}; x<xmax; x+=xstep ){

lw.write( std::to_string(x) + " " + std::to_string( std::sin(x) ) );

if (first){

first = false;

gp.sendLine( plotCommand.str() );

gp.flush();

} else {

gp.sendLine("replot");

gp.flush();

}

std::this_thread::sleep_for(std::chrono::milliseconds(sleep_ms));

}

return 0;