class File

Outline

File class is the class which reads and writes files and has static methods. And also by new File(filename, attr) you can create an instance for a specific file as you specifyed.

Static Methods

The static methods of File class is below.

Method	Outline	Return Value(Type)	Arguments	Meaning
File.load(path)	Read all contents of a text file.	String	path: String	File path to be read.
File.mkdir(path)	Make a directory.	1: Success	path: String	Directory path to be created.
File.rename(oldname, newname)	Change a file name.	1: Success	oldname: String	File path before changed.
			newname: String	File path after changed.
File.unlink(path)	Remove a file.	1: Success	path: String	File path to be removed.
File.exists(path)	Check if a file exists.	1: Exists	path: String	File path to be checked.
File.isDirectory(path)	Check if it is a directory.	1: The file is directory.	path: String	File path to be checked.
File.isSymlink(path)	Check if it is a symbolic link.	1: The file is symbolic link.	path: String	File path to be checked.
File.filesize(path)	Return a file size.	Integer	path: String	File path to be checked.
File.filedate(path)	Return a date and time of a file.	{ modified, accessed, creation }	path: String	File path to be checked.
File.setFiledate(path, obj)	Set a date and time of a file.		path: String	File path to be checked.
			obj: Object	{ modified, accessed, creation }

File Instance

An instance of the File is created by new. Here is an example.

var f = new File(filename, attr);

The following parameters are passed to a constructor.

Parameter	Values	Meaning
filename	String	File name
attr	File.READ	Readable
	File.WRITE	Writable
	File.APPEND	Append mode
	File.TEXT	Text mode
	File.BINARY	Binary mode

• The followins are how to use attributes to open file.
  • File.READ|File.APPEND… Readable and Append mode.
  • File.READ|File.WRITE … Readable and Writable, and the file will be newly created.
  • File.READ|File.TEXT … Read only with Text mode.

A File instance has following methods.

Method	Outline	Return Value(Type)	Arguments	Meanning
f.load()	Read all contents of a file.	String
f.close()	Close a file.
f.readLine()	Read a line.	String, 0: EOF
f.peek(ms)	Check if there is an input.	1: Exists, 0: Not exists	ms: Integer	Timeout in milliseconds.
f.getch()	Read a character.	Integer as a character code.
f.putch(ch)	Put a character.		ch: Integer	Integer as a character code to output.
f.print(...args)	Output a string without newline.	Output count: Integer	…args	Items to be output.
f.println(...args)	Output a string with newline.	Output count: Integer	…args	Items to be output.

File.open()

If you create an instance of File class, you have to do close at the end. GC will automatically close a file, but it can not be controlled a moment of closing. File.open method is useful when you want to close the file after exiting a scope.

Here is an example.

File.open("README.md", File.READ, &(f) => {
    var l, n = 0;
    while ((l = f.readLine()).isString) {
        System.println("%4d: %s" % (++n) % l);
    }
});

File.open implementation is almost same as below.

function FileOpen(filename, attr, func) {
    var f = new File(filename, attr);
    try {
        return func(f);
    } finally {
        f.close();
    }
}

Examples

Example 1. Static methods (1)

Code

System.try({ => File.remove("TEMPTESTDIR") }).retry(5, 250).else() if (File.exists("TEMPTESTDIR"));
System.try({ => File.remove("TEMPTESTDIR2") }).retry(5, 250).else() if (File.exists("TEMPTESTDIR2"));

File.mkdir("TEMPTESTDIR") if (!File.exists("TEMPTESTDIR"));
System.println(File.isDirectory("TEMPTESTDIR"));

Result

1

Example 2. Static methods (2)

Code

File.remove("TEMPTESTDIR2") if (File.exists("TEMPTESTDIR2"));
File.rename("TEMPTESTDIR", "TEMPTESTDIR2");
System.println(File.exists("TEMPTESTDIR"));
System.println(File.exists("TEMPTESTDIR2"));

Result

0
1

Example 3. Static methods (3)

Code

for (var i = 0; i < 10; ++i) {
    File.open("TEMPTESTDIR2/test.txt", File.READ|File.WRITE|File.APPEND) { &(f)
        f.println("[%d] This is a sample file." % i);
    };
}
System.println(File.load("TEMPTESTDIR2/test.txt"));

Result

[0] This is a sample file.
[1] This is a sample file.
[2] This is a sample file.
[3] This is a sample file.
[4] This is a sample file.
[5] This is a sample file.
[6] This is a sample file.
[7] This is a sample file.
[8] This is a sample file.
[9] This is a sample file.

Example 4. Static methods (4)

Code

File.open("TEMPTESTDIR2/test.txt", File.READ|File.TEXT) { &(f)
    var l, n = 0;
    while ((l = f.readLine()).isString && l.length() > 0) {
        System.println("* %2d: %s" % (++n) % l);
    }
};

Result

*  1: [0] This is a sample file.
*  2: [1] This is a sample file.
*  3: [2] This is a sample file.
*  4: [3] This is a sample file.
*  5: [4] This is a sample file.
*  6: [5] This is a sample file.
*  7: [6] This is a sample file.
*  8: [7] This is a sample file.
*  9: [8] This is a sample file.
* 10: [9] This is a sample file.

Example 5. Static methods (5)

Code

System.println(File.exists("TEMPTESTDIR2/test.txt"));
File.remove("TEMPTESTDIR2/test.txt");
System.println(File.exists("TEMPTESTDIR2/test.txt"));

Result

1
0