Author Archive

Angular Services in CoffeeScript

August 15th, 2013 1 comment

This jsbin demonstrates how to use a CoffeeScript class to implement an Angular Service, using Service, Factory and Provider styles. You may have to click “Run with JS” to update Output pane. Download gist from github.

Update: by itself this is not enough, since services usually have to inherit other resources, and look something like this:

.service('thumbService', ['$log', '$q', ($log, $q) ->

A working example (using .factory instead of .service) from the angular-grunt-coffeescript seed app:

Example of a service shared across views.
Wrapper around the data layer for the app. 
name = ''

class DataSvc

	constructor: (@$log, @$http, @env) ->

	_get: (relPath)->
		return @$http.get("#{@env.serverUrl}/#{relPath}")

	getPeople: () ->
		return @_get('people')

	getPerson: (id) ->
		return @_get("person/#{id}")

angular.module(name, []).factory(name, ['$log','$http', '', ($log, $http, env) ->
	new DataSvc($log, $http, env)

Go uintptr from interface{}

June 28th, 2013 No comments

Some C functions accept more than one type of struct, so I wanted a Go wrapper able to pass a uintptr derived from an interface{}. Go’s reflect package makes this easy:

package main

import (

type USN_JOURNAL_DATA struct {
  UsnJournalID    int
  FirstUsn        uint32
  NextUsn         uint32
  LowestValidUsn  uint32
  MaxUsn          uint32
  MaximumSize     uint32
  AllocationDelta uint32

func doitA(ujd *USN_JOURNAL_DATA) (size uintptr, align int, p uintptr) {
  v := reflect.ValueOf(ujd)
  t := v.Elem().Type()
  size = t.Size()
  align = t.Align()
  p = v.Pointer()

func doitB(i interface{}) (size uintptr, align int, p uintptr) {
  v := reflect.ValueOf(i)
  t := v.Elem().Type()
  size = t.Size()
  align = t.Align()
  p = v.Pointer()

func main() {
  a := USN_JOURNAL_DATA{1, 2, 3, 4, 5, 6, 7}
  size, align, p := doitA(&a)
  fmt.Println(size, align, p)
  size, align, p = doitB(&a)
  fmt.Println(size, align, p)

Interestingly, as demonstrated above, the same implementation can be used for a func accepting either a struct pointer or an interface{}.

Go import

June 18th, 2013 No comments

Go is a wonderful language, able to build complex applications with very minimal configuration information. For many apps, only import statements are required.

However, there are a couple of special import cases worth knowing about:

import . “”

From “If a program imports a standard package using import . “path”, additional names defined in the imported package in future releases may conflict with other names defined in the program. We do not recommend the use of import . outside of tests, and using it may cause a program to fail to compile in future releases.”

import _ “”

From Andrew Gerrand (Google): “Prefixing an import
with an underscore causes the package to be imported for its
side-effects only. (that is, it’s init functions are executed and
global variables initialized)”

Categories: Development Tags: ,

Raspberry Pi & Cubieboard Benchmarks

January 17th, 2013 No comments
Simple write test: dd bs=1M count=1000 if=/dev/zero of=test
Ignore first run results
Copy of 13,000+ files: cp -a /var/* …
Raspberry Pi
android (busybox to nvram)
4.8 M/B/s
berryboot (raspbian squashfs) 4G(c4)
200M 16 +/- .5MB/s 7.8 +/- .1 MB/s
1G 11 +/- .5MB/s 8.3 +/- 1 MB/s
200M to SATA HD 63 +/- 2MB/s
1G to SATA HDD 45 +/- 2MB/s
13,727 files (/usr) from SD -> HDD (ext4) 9.2 sec
13,727 files (/usr) from HDD -> SD 38 sec
debian (drazbian) 16G(c10)
200M 22 +/- 2 MB/s
1G 7.6 +/- .5 MB/s
Categories: Linux Tags: , , , ,

Make squashfs Disk Image

January 17th, 2013 1 comment

Raspberry Pi (and Cubieboard) SD disk images typically have two (or three) partitions: the first is Fat32 (50-100MB) and includes the boot files, while the second (>1GB) contains the main Linux image. With compression, the combined image can be reduced from several GB (of mostly empty space) to a couple hundred MB.

With a regular Linux desktop computer that has kpartx and mksquashfs installed, you can convert the second partition to SquashFS like this:

$ sudo kpartx -av image_you_want_to_convert.img
add map loop0p1 (252:5): 0 117187 linear /dev/loop0 1
add map loop0p2 (252:6): 0 3493888 linear /dev/loop0 118784
$ sudo mount /dev/mapper/loop0p2 /mnt
$ sudo mksquashfs /mnt converted_image.img -comp lzo -e lib/modules
$ sudo umount /mnt
$ sudo kpartx -d image_you_want_to_convert.img

dd with gzip

January 16th, 2013 No comments

You can save a lot of space by compressing dd image files.
These examples use gzip but many other compression apps will work just as well.

backup with dd and gzip

dd if=/dev/wd0a | gzip -9 > /mnt/backup.gz

restore backup

gunzip /mnt/backup.gz – | dd of=/dev/wd0a

Categories: Linux, OS X Tags: , , , , , ,

XCode and Older iOS Devices

January 16th, 2013 No comments

With a bit of hacking, it’s possible to target older iOS devices than those normally supported by the latest SDK:

Categories: Development, OS X Tags: , , , , , , , ,

SourceTree from Command Line

January 16th, 2013 No comments

Download SourceTree command line tools from:

To open repo in current folder:

stree .

Categories: Development, OS X Tags: , , ,

Github Fork

January 16th, 2013 No comments

Configure remotes

To keep track of the original repo, you need to add another remote named upstream:

cd Spoon-Knife
git remote add upstream # Assigns the original repo to a remote called “upstream”

Pull in upstream changes

If the original repo you forked your project from gets updated, you can add those updates to your fork by running the following code:

git fetch upstream                     # Fetches any new changes from the original repo
git merge upstream/master    # Merges any changes fetched into your working files

Categories: Development Tags: , , , , ,

git Submodule

January 16th, 2013 No comments

replace submodule repo

You should just be able to edit the .gitmodules file to update the URL and then run git submodule sync to reflect that change to the superproject and your working copy.

recursive submodule init and update

git submodule update –init –recursive

update only

git submodule update –recursive

recursive add submodule

git submodule add foo
git submodule update –init –recursive

Categories: Development Tags: , , ,