bytecode

How is pattern matching in Scala implemented at the bytecode level? Is it like a series of if (x instanceof Foo) constructs, or something else? What are its performance implications? For example, given the following code (from Scala By Example pages 46-48), how would the equivalent Java code for the eval method look like? abstract class Expr case class Number(n: Int) extends Expr case class Sum(e1: Expr, e2: Expr) extends Expr def eval(e: Expr): Int = e match { case Number(x) => x case Sum(l, r) => eval(l) + eval(r) } P.S. I can read Java bytecode, so a bytecode representation would be good

I would like to know how can I check if a compiled Java class contains debug symbols. The problem is that I compile an application from ant with debug="on", but a specific JVM throws an exception: it says that the debug symbols are missing. Thanks. If you run javap -v on the class file, you will see the debug information that is present in the file. It is worth compiling a simple test class with different -g option settings and looking at the results with javap . If, you need to know exactly how javap presents the information, it is it is best for you to try it out in your Java installation.

I am looking at some disassembled code obtained from Java bytecode. I see some declaration as follows: .method static synthetic access$0()Lcom/package/Sample; I am not able to figure out what the synthetic or access$0 mean. Can someone please help me understand this part? Johan Sjöberg Synthetic field , (2) A compiler-created field that links a local inner class to a block's local variable or reference type parameter. See also The JavaTM Virtual Machine Specification (§4.7.6) or Synthetic Class in Java . In the java language, inner classes can access private members of their enclosing class.

Say I have a string in php, that prints out to a text file like this: nÖ§9q1Fª£ How do I get the byte codes of this to my text file rather than the funky ascii characters? Use the ord function http://ca.php.net/ord eg. <?php $var = "nÖ§9q1Fª£ˆæÓ§Œ_»—Ló]j"; for($i = 0; $i < strlen($var); $i++) { echo ord($var[$i])."<br/>"; } ?> If You wish to get the string as an array of integer codes, there's a nice one-liner: unpack('C*', $string) Beware, the resulting array is indexed from 1, not from 0! Adee If you are talking about the hex value, this should do for you: $value = unpack('H*', "Stack");

I don't really get the concept of "bytecode interpreter" in the context of CPython. Can someone shed some light over the whole picture? Does it mean that CPython will compile and execute pyc file (bytecode file?). Then what compile py file to pyc file? And how is Jython different from CPython (except they are implemented in different languages). I also read somewhere that Python is C++ interpretation. Is this correct? And what does that mean? I'm still very new to Python, so forgive me if I ask the dumb questions... Thank you so much! CPython is the implementation of Python in C. It's the