Skip to main content

Debugging Lift 2.4 with Eclipse

To continue my last post, launching a Lift program and debugging from Eclipse turns out to be straightforward.

The starting point was this stackoverlow thread which pointed out the existence of the RunJettyRun Eclipse plugin, which can launch a Jetty instance from within Eclipse configured for remote debugging. Here are the steps to get launching and debugging working seamlessly:

  1. Install RunJettyRun from within Eclipse the usual way, ie. menu Help > Install New Software, then copy-paste this link.
  2. Once installed, go to menu Run > Debug Configurations, and double-click Jetty Webapp. This will create a new configuration for this project.
  3. Click Apply to save this configuration, and you can now start debugging to your heart's content.

NOTE: running Jetty in SBT via ~container:start puts the web app in the root of the web server, ie. http://localhost:8080/, but this plugin defaults to http://localhost:8080/project_name. You can change this via the "Context" parameter in the debug configuration. This defaults to the project name, presumably so you can run/debug multiple web apps simultaneously.

Labels:

Comments

Post a Comment

Popular posts from this blog

Blue-eyed Islander Puzzle - an analysis

Many people find themselves stumped by the so-called Blue-Eyed Islanders puzzle . There is also much controversy over its supposed solution. I'm going to analyze the problem and the solution, and in the process, explain why the solution works. To begin, let's modify the problem slightly and say that there's only 1 blue-eyed islander. When the foreigner makes his pronouncement, the blue-eyed islander looks around and sees no other blue eyes, and being logical, correctly deduces that his own eyes must be blue in order for the foreigner's statement to make sense. The lone blue-eyed islander thus commits suicide the following day at noon. Now comes the tricky part, and the source of much confusion. Let's say there are 2 blue-eyed islanders, Mort and Bob. When the foreigner makes his pronouncement, Mort and Bob look around and see only each other. Mort and Bob thus both temporarily assume that the other will commit suicide the following day at noon. Imagine their chagrin...
40 comments
Read more

Easy Reverse Mode Automatic Differentiation in C#

Continuing from my last post on implementing forward-mode automatic differentiation (AD) using C# operator overloading , this is just a quick follow-up showing how easy reverse mode is to achieve, and why it's important. Why Reverse Mode Automatic Differentiation? As explained in the last post, the vector representation of forward-mode AD can compute the derivatives of all parameter simultaneously, but it does so with considerable space cost: each operation creates a vector computing the derivative of each parameter. So N parameters with M operations would allocation O(N*M) space. It turns out, this is unnecessary! Reverse mode AD allocates only O(N+M) space to compute the derivatives of N parameters across M operations. In general, forward mode AD is best suited to differentiating functions of type: R → R N That is, functions of 1 parameter that compute multiple outputs. Reverse mode AD is suited to the dual scenario: R N → R That is, functions of many parameters t...
18 comments
Read more

Extensible, Statically Typed Pratt Parser in C#

I just completed a statically typed Pratt-style single-state extensible lexer+parser, otherwise known as a top-down operator precedence parser, for the Sasa library . The implementation is available in the Sasa.Parsing dll, under Sasa.Parsing.Pratt . Two simple arithmetic calculators are available in the unit tests . This implementation is novel in two ways: Aside from an alleged implementation in Ada , this is the only statically typed Pratt parser I'm aware of. Pratt parsers typically require a pre-tokenized input before parsing semantic tokens, but I've eliminated this step by using the symbol definitions to drive a longest-match priority-based lexer. Symbols by default match themselves, but you can optionally provide a scanning function used to match arbitrary string patterns. The symbol selected for the current position of the input is the symbol that matches the longest substring. If two symbols match equally, then the symbol with higher precedence is selected. The design...
12 comments
Read more