[bonzoesc]

It doesn't really taste like syntactic sugar though; it's a special functionality of the standard library, and you could easily get away without knowing about the Java/C-style API of keeping a file handle that has to be controlled around.

[CodeMage]

Out of the three languages he mentions as having syntactic sugar, he was wrong only in Ruby's case. Like you said, it's not a specific syntactic sugar for Dispose pattern, unlike C#'s "using" and Python's "with".

[JoachimSchipper]

Honest question: what's the difference between Ruby and Python/C# here?

[CodeMage]

Let's look at rst's example:

   File.open("...") do |f|
     ... stuff that might throw an exception ...
   end

The syntax you see here is for passing a block to a method. In this case, you're passing a block to File.open, which opens the file, executes your block with it and then makes sure to close the file no matter what.

In Python, you would do:

   with open("x.txt") as f:
     ... stuff that might throw an exception ...

What this does is evaluate open("x.txt"), call the __enter__ method on the resulting value (called the context guard), assign the result of the __enter__ method to f, executes the body of the with statement and makes sure to call __exit__ method of the guard.

The difference is that the syntax used in the Ruby example uses is not syntactic sugar for Dispose pattern, it's part of Ruby's syntax for working with blocks in general, whereas the syntax used in Python example is syntactic sugar meant for Dispose pattern (but can be used for other stuff too).