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wren/doc/site/modules/io/file.markdown
2016-01-01 10:05:31 -08:00

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^title File Class
Lets you work with files on the file system. An instance of this class
represents an open file with a file descriptor.
When you are done with a file object, it's a good idea to explicitly close it.
If you don't, the GC will close it when the file is no longer used and gets
finalized, but that may take a while. In the meantime, leaving it open wastes
a file descriptor.
## Static Methods
### File.**open**(path, fn)
Opens the file at `path` and passes it to `fn`. After the function returns, the
file is automatically closed.
:::wren
File.open("words.txt") {|file|
file.readBytes(5)
}
### File.**read**(path)
Reads the entire contents of the file at `path` and returns it as a string.
:::wren
File.read("words.txt")
The encoding or decoding is done. If the file is UTF-8, then the resulting
string will be a UTF-8 string. Otherwise, it will be a string of bytes in
whatever encoding the file uses.
### File.**size**(path)
Returns the size in bytes of the contents of the file at `path`.
### File.**stat**(path)
"Stats" the file or directory at `path`. Returns a [Stat][] object describing
the low-level details of the file system entry.
[stat]: stat.html
## Constructors
### File.**open**(path)
Opens the file at `path` for reading.
## Methods
### **descriptor**
The numeric file descriptor used to access the file.
### **isOpen**
Whether the file is still open or has been closed.
### **size**
The size of the contents of the file in bytes.
### **close**()
Closes the file. After calling this, you can read or write from it.
### **readBytes**(count)
Reads up to `count` bytes starting from the beginning of the file.
:::wren
// Assume this file contains "I am a file!".
File.open("example.txt") {|file|
System.print(file.readBytes(6)) //> I am a
}
### **readBytes**(count, offset)
Reads up to `count` bytes starting at `offset` bytes from the beginning of
the file.
:::wren
// Assume this file contains "I am a file!".
File.open("example.txt") {|file|
System.print(file.readBytes(6, 2)) //> am a f
}