Description Peter Salzman 2008-03-07 12:34:50 EST

Debugging under Eclipse is extremely painful.

I work with numerical code.  Lots of calculations that pull coefficients from a database that need to be debugged.  Speed of debugging is essential since there's usually so many things that need to be checked.

I'm used to Visual Studio, where the value of a variable pops up when the mouse cursor hovers over a variable.  This way I don't need to formally place tons of variables in a "watch list".  Eclipse does this too, but with unreasonable restrictions.

For example, consider this code:

MyClass.FooFactors foo = MyClass.getFooFactors( CASE_DEGENERATE );
MyClass.BarFactors bar = MyClass.getBarFactors( CASE_DEGENERATE );
FooBarClass.FBF    fbf = FooBarClass.getFBF( PERTURBATIVE );

for ( ... )
x[i] = foo.intercept + ln(bar.intercept) + fbf.ycept + exp(foo.x1)/(exp(foo.x2) + 1) + bar.propother + probit_transformation(fbf.rating) - ...

Since foo is a class, I wouldn't expect to see anything if I let the mouse hover over it.  Eclipse will pop up the name of the class that foo is an instance of (or if I'm making a reference to the class itself, it'll give the package name).  That's good.

What is unforgivable, however, is what happens when I let the mouse hover over ".intercept" in "foo.intercept".  I would expect the value of foo.intercept to pop up when the mouse hovers over the ".intercept" part of "foo.intercept".  It's a double.  Eclipse knows its current value with 100% certainty.  The value is sitting right there on the stack frame (or however Java programs are organized in memory).  I can even get the value by highlighting "foo.intercept" and using ctl-shft-d (to display) or ctl-shft-i (to inspect).  Or I could add foo to the watch list and see the value that way.

But I have hundreds of these things, and sometimes, I need to check each one.  Highlighting is surgeon's task here: including the semi-colon is an error.  Not highlighting the fully qualified variable (ie highlighting "intercept" rather than "foo.intercept") is an error.   And then I must use either two mouse clicks or take my hand off the mouse and put it on the keyboard.


It doesn't even have to be something as "exotic" as a class.  Even a simple array has the same problem:

public class Foo
{
   public static void main( String[] args )
   {
      int i;
      int j[] = new int[5];

      for ( i = 0; i < 5; ++i ) {
         j[i] = i;
         System.out.println("hello world");
      }
   }
}


Set a breakpoint at the println statement and debug the program in Eclipse.  Let the mouse hover over the "i", and Eclipse will pop up "0".  Now let the mouse hover over j[i].  You'd think Eclipse would pop up "0" since i=0 and j[0]=0, but it doesn't.  It pops up "j=int[5]", which is not all that helpful.

If Eclipse *can* know the value of a variable, it really *ought* to report the value of that variable in a manner convenient for the programmer.  Inspecting is fine when you have a complicated class object you want to look at.  Watch lists are fine when you want to see how a variable changes in time.  However, if I have a double valued member of a class, Eclipse really should simply display the value.

Also, highlighting variables to display, watch, or inspect them is very painful as well.   If I have a variable that I'd like to watch, say:

     double someDoubleVariable = 0.0
     someDoubleVariable = someClassInstance.someArray[j];

and I'd like to inpsect someArray, what I need to do is highlight "someClassInstance.someArray[j]".  The semi-colon is not allowed.  Missing the "s" in "someClassInstance" is not allowed.

Really, Eclipse should be smart enough for me to rightclick **anyway** in the string "someArray" and put the array in a watchlist.  There's really no need to highlight the whole thing.  I'm sure Eclipse could do that.

Thanks.