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Files

Table of contents

  1. Files
    1. Opening files
    2. Writing to files
    3. Reading files
    4. Seek(number, number: from -> optional)

Files

Opening files

Opening files is very easy in Dictu. Syntax is with(<file name>, <open mode>) {}. Inside the with block, file is declared as a constant for you, and is the file object which has just been opened. Dictu will handle closing the file for you and happens when you leave the with scope automatically. Note, the path when opening files is relative to the process not the current script running.

Open Mode Description
r Opens a file for reading, the file must exist already.
w Opens a file for writing, if a file does not exist one is created, else existing file is overwritten.
a Opens a file for appending, if a file does not exist one is created, else appends text to the end of a file.
r+ Opens a file for updating (read + write), the file must exist already.
w+ Opens a file for updating (read + write), if a file does not exist one is created, else existing file is overwritten
a+ Opens a file for updating (read + write), if a file does not exist one is created, else appends text to the end of a file.
with("test.txt", "r") {
    // file var is passed in here
}

// file is out of scope, and will the file will be closed for you

Writing to files

There are two methods available when writing to a file: write() and writeLine(). write() simply writes strings to a file, writeLine() is exactly the same, except it appends a newline to the passed in string. Both functions return the amount of characters wrote to the file.

with("test.txt", "w") {
    // file var is passed in here
    file.writeLine("Hello!"); // 6
    file.write("Hi"); // 2
}

// file is out of scope, and will be closed for you here

Reading files

There are two methods available when reading files: read() and readLine(). read() reads the entire file, and returns its content as a string. readLine() will read the file up to a new line character.

// Read entire file
with("test.txt", "r") {
    print(file.read());
}
// Read a file line by line
with("test.txt", "r") {
    var line;
    // When you reach the end of the file, nil is returned
    while((line = file.readLine()) != nil) {
        print(line);
    }
}

Another method which may come in useful when reading files is seek(). seek() allows you to move the file cursor so you can re-read a file, for example, without closing the file and reopening.

Seek(number, number: from -> optional)

Both arguments passed to seek need to be of numeric value, however the from argument is optional. The first argument (offset) is the amount of characters you wish to move from the cursor position (negative offset for seeking backwards). The second argument (from) is for controlling where the cursor will be within the file, options are 0, 1 or 2.

  • 0 => Seek from the start of the file.
  • 1 => Seek from the current cursor position.
  • 2 => Seek from the end of the file.

If the from parameter is not supplied, seek() will occur from the beginning of the file.

with("test.txt", "r") {
    print(file.read());
    file.seek(0); // Go back to the start of the file
    print(file.read());
    file.seek(-5, 1); // Go back 5 from current position
    print(file.read());
    file.seek(0); // Go to the start of the file
    file.seek(-5, 2); // Go to the end of the file, and then 5 places back
    print(file.read());
}

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