fpmas::io::FileOutput Class Reference

#include <output.h>

Inheritance diagram for fpmas::io::FileOutput:

Collaboration diagram for fpmas::io::FileOutput:

Public Member Functions
	FileOutput ()
	FileOutput (std::string filename, std::ios::openmode mode=std::ios::out)
	FileOutput (std::string file_format, int rank, std::ios::openmode mode=std::ios::out)
	FileOutput (std::string file_format, api::scheduler::TimeStep step, std::ios::openmode mode=std::ios::out)
	FileOutput (std::string file_format, int rank, api::scheduler::TimeStep step, std::ios::openmode mode=std::ios::out)
std::ofstream &	get () override
Public Member Functions inherited from fpmas::api::io::OutputStream
virtual std::ostream &	get ()=0
std::ostream &	operator<< (std::ostream &(*func)(std::ostream &))

Detailed Description

An helper class that can be used to initialize a file output stream.

This class is notably useful to extend output classes that take an output stream as constructor parameter, such as CsvOutput.

For example, the following code is wrong and will produce a segmentation fault:

class MyOutput : public fpmas::io::CsvOutput<int> {
    private:
        fpmas::io::FileOutput file("file.csv");
 
    public:
        MyOutput()
            : fpmas::io::CsvOutput<int>(
                this->file, 
                {"my_field", [] () {return ...}}
                ) {}
};

Indeed, the CsvOutput constructor uses the specified output stream (to automatically write CSV headers), BUT CsvOutput, as a base class of MyOutput, is initialized before MyOutput, so before file, what produces a segmentation fault.

This FileOutput class can be used to easily solve the issue:

// FileOutput must be specified BEFORE CsvOutput
class MyOutput : public fpmas::io::FileOutput, fpmas::io::CsvOutput<int> {
    public:
        MyOutput() :
            fpmas::io::FileOutput("file.csv"),
            fpmas::io::CsvOutput<int>(
                *this,
                {"my_field", [] () {return ...}}
                ) {}
};

In this case, FileOutput is properly initialized before CsvOutput so no error occurs.

Constructor & Destructor Documentation

FileOutput() [1/5]

fpmas::io::FileOutput::FileOutput ( )

inline

Default constructor.

The underlying file is left in an undefined state.

FileOutput() [2/5]

fpmas::io::FileOutput::FileOutput	(	std::string	filename,
		std::ios::openmode	mode = std::ios::out
	)

FileOutput constructor.

The underlying file is opened only when get() is called.

See also

https://en.cppreference.com/w/cpp/io/basic_filebuf/open

Parameters

filename	file name
mode	standard open mode

FileOutput() [3/5]

fpmas::io::FileOutput::FileOutput	(	std::string	file_format,
		int	rank,
		std::ios::openmode	mode = std::ios::out
	)

FileOutput constructor.

file_format is formatted using fpmas::utils::format(std::string, int) to produce a file name.

The underlying file is opened only when get() is called.

See also

https://en.cppreference.com/w/cpp/io/basic_filebuf/open

Parameters

file_format	file name to format
rank	rank of the current process
mode	standard open mode

FileOutput() [4/5]

fpmas::io::FileOutput::FileOutput	(	std::string	file_format,
		api::scheduler::TimeStep	step,
		std::ios::openmode	mode = std::ios::out
	)

FileOutput constructor.

file_format is formatted using fpmas::utils::format(std::string, fpmas::api::scheduler::TimeStep) to produce a file name.

The underlying file is opened only when get() is called.

See also

https://en.cppreference.com/w/cpp/io/basic_filebuf/open

Parameters

file_format	file name to format
step	current time step
mode	standard open mode

FileOutput() [5/5]

fpmas::io::FileOutput::FileOutput	(	std::string	file_format,
		int	rank,
		api::scheduler::TimeStep	step,
		std::ios::openmode	mode = std::ios::out
	)

FileOutput constructor.

file_format is formatted using fpmas::utils::format(std::string, int, fpmas::api::scheduler::TimeStep) to produce a file name.

The underlying file is opened only when get() is called.

See also

https://en.cppreference.com/w/cpp/io/basic_filebuf/open

Parameters

file_format	file name to format
rank	rank of the current process
step	current time step
mode	standard open mode

Member Function Documentation

get()

std::ofstream & fpmas::io::FileOutput::get ( )

overridevirtual

Returns a reference to the internal file output stream, that can be used to output data using the classical C++ << operator.

The file is open once, the first time this get() method is called.

This allows the FileOutput object to be declared on all processes, while being opened only on one process, assuming only one process is writing to the file, preventing other processes to delete the file content when it is opened if the current openmode is out.

Returns

file output stream

Implements fpmas::api::io::OutputStream.

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The documentation for this class was generated from the following files:

• src/fpmas/io/output.h
• src/fpmas/io/output.cpp