Suggestion for emulating the open() function in Python (file handling)

[serge-hulne]

Proposal

A simple suggestion for emulating the open() function of Python.
as in

f = open("demofile.txt", "r")
for x in f:
  print(x)

Background

Aim: Reading a file line by line in order to avoid reading a very large file all at once (to save RAM).

Workarounds

reading a file, line by line in a for loop can be done in Go the following way

func Open(fname string) (error, *os.File) {
	file, err := os.Open(fname)
	check(err)
	return err, file
}

func Close(file *os.File) {
	file.Close()
}

func ReadLines(f *os.File) chan string {
	ch_lines := make(chan string)
	go func() {
		defer close(ch_lines)
		scanner := bufio.NewScanner(f)
		for scanner.Scan() {
			ch_lines <- scanner.Text()
		}
	}()
	return ch_lines
}

Examples of use:

	_, f := fi.Open("text.txt")
	lines := fi.ReadLines(f)
        for line := range lines {
              println(line)
        }

more details here:
https://github.com/serge-hulne/goutils/blob/main/files/fileutils.go

[xushiwei]

import "os"

for line <- os.Stdin {
	println line
}

and Go+ provides builtin functions open and create for os.File.

[xushiwei]

% cat foo.gop

for line <- open("foo.gop")! {
    println line
}

% gop run foo.gop

for line <- open("foo.gop")! {
    println line
}