better.files.File#lines does not close the file

[holgerbrandl]

Example:

val someFile = File("test.txt")
someFile.write("tt")

for(a<-1 to 10000) {
    someFile.lines
}

will die inevitably with a "Too many open files in system" error.

The solution would be to use some closable or even simpler to use Files.readAllLines instead of Files.lines

See also
http://www.rationaljava.com/2015/02/java-8-pitfall-beware-of-fileslines.html
https://bugs.openjdk.java.net/browse/JDK-8073923

[pathikrit]

I think auto closable is the right way here. If file has a lot of lines (say a log file), it may cause an OOM with File.readAllLines

[holgerbrandl]

It might be hard to implement it that way since b.f.File.lines is returning an iterator (which is nice since it allows for very elegant programming). I've not much knowledge about auto-closables but I thought when using them, the consumption of the file content would need to happen in a scope, which would reduce the beauty/readability of File.lines.

I totally agree about potential performance issues when using java.nio.Files.allLines as backend for b.f.File.lines but at least programs would not die after a while when using it. The provided links indicate that nio.Files.lines API design is misleading to many users and maybe b.f could do a better job by providing

• a file line iterator (e.g. .linesIterator) by which enforces file closing via some auto-closable.
• a more simplistic .lines method which simply returns a List[String]