Fletch 0.1.0 documentation

tool.md

+---
+title: Fletch tool details
+layout: page
+---
+
+# Fletch tool details
+
+## Running code locally and remotely
+
+In the [getting started instructions](index.html) we tried running programs both
+on the local PC, and on a remote Raspberry Pi. Are you curious how that works in
+details?
+
+When you run a program with ```fletch run``` it always runs in a 'session'. You
+can specify the name of the session with an additional argument after run:
+```fletch run in session <session name>```. If you omit the session argument,
+then the tool defaults to the ```local``` session where the program is run on
+the local PC.
+
+The settings for these sessions are defined in configuration files located in
+the path ```<user home directory>/<session name>.fletch-settings```. If you take
+a look at the remote settings file, you will see this content (exact path and
+IP will differ on your PC):
+
+~~~
+{
+  "packages": "file:///Users/mit/fletch-sdk/internal/fletch-sdk.packages",
+  "options": [],
+  "constants": {},
+  "device_address": "192.168.2.2:12121"
+}
+~~~
+
+The ```device_address``` tag tells fletch where to locate the VM Agent on your
+attached device. If the IP of that device changes, then you need to update this
+tag. If the value is omitted or set to null, Fletch will run locally.
+
+## Debugging
+
+Fletch also supports debugging. Let's try to debug the Knight Rider sample.
+Start by running the following command in your terminal:
+
+~~~
+debug $HOME/fletch-sdk/samples/raspberry_pi/basic/knight-rider.dart in session remote
+~~~
+
+You should see the terminal change to:
+
+~~~
+Starting session. Type 'help' for a list of commands.
+
+>
+~~~
+
+Let's set a breakpoint in the _setLeds method, and start the execution of the
+program:
+
+~~~
+b _setLeds
+r
+~~~
+
+We are now inside the _setLeds method. Let's see what the initial state is: Type ```p```. You should see this output
+
+~~~
+ledToEnable: 0
+this: Instance of 'Lights'
+>
+~~~
+
+Try to step a few more times (with the ```s``` command), and then print out the
+local variable again (with the ```p``` command). You should see ledToEnable
+increment up to the numner of LEDs you have, and then you should see it start
+decrementing. Pretty neat right!?