Semicolons in Javascript

I read this very interesting blog post today and kind of made me thinking .. 

Semicolons in JavaScript are optional - http://mislav.uniqpath.com/2010/05/semicolons/ by Mislav Marohnić (http://mislav.uniqpath.com/) 

Centralize a Tile based view

A project that I'm working on has a structure similar to what you seen in Pinterest. Except that the height of the Tiles do not vary as in Pinterest.

What happens essentially in Pinterest is that the Tiles are positioned absolutely. The Tiles are given left and top css properties and are positioned according with resize handlers.

But in this application, the height of the Tile is static. Therefore we could accomplish this with CSS and some javascript. One knows the width of the Tile (Look at Jquery's outerWidth) and the width of the window (Look at Jquery's width). One just has to set up a resize handler (Look at Jquery's resize) and do something similar to this.

var base = $('#content_wrapper'), window_width, post_width; 
if(base.length !== 0) { 
 window_width = $(window).width();
 post_width = $('.post:first').outerWidth(true); 
 if(window_width%post_width !== 0) {
  base.css({'width': window_width - (window_width%post_width)}); 
 } else { 
  base.css({'width': window_width}); 
 } 
} 

$(window).resize(function() { 
 // Call the function here .. 
});

We will also need to call the function when the page loads too for the initial set up.

Compiling Ruby 1.9.2 with OS X 10.7

I had to setup a machine which ran 10.7 with Ruby 1.9.2 because the application ran on this version. It was a rails application of version 3.1.

I tried to get the machine set up with rbenv which went smooth.

I tried to do a

rbenv install 1.9.2-p180

Which did not go well at all.

I got errors like

/usr/bin/gcc-4.2 -dynamic -bundle -o ../../../.ext/x86_64-darwin11.3.0/racc/cparse.bundle cparse.o -L. -L../../.. -L/Users/jasonvdm/.rvm/usr/lib -L. -L/usr/local/lib -Wl,-undefined,dynamic_lookup -Wl,-multiply_defined,suppress -Wl,-flat_namespace  -lruby.1.9.1  -lpthread -ldl -lobjc 
compiling readline/usr/bin/gcc-4.2 -I. -I../../.ext/include/x86_64-darwin11.3.0 -I../.././include -I../.././ext/readline -DRUBY_EXTCONF_H=\"extconf.h\" -I/Users/jasonvdm/.rvm/usr/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE   -fno-common -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wpointer-arith -Wwrite-strings -Wno-missing-field-initializers -Wshorten-64-to-32 -Wno-long-long  -fno-common -pipe  -o readline.o -c readline.c
readline.c: In function ‘username_completion_proc_call’:
readline.c:1386: error: ‘username_completion_function’ undeclared (first use in this function)
readline.c:1386: error: (Each undeclared identifier is reported only once
readline.c:1386: error: for each function it appears in.)
make[1]: *** [readline.o] Error 1
make: *** [mkmain.sh] Error 1

Which essential means that I needed to update the readline library to this error out of the way. I started out by downloading the readline version 6.1 manually and installing but that failed miserably.

curl -O ftp://ftp.gnu.org/gnu/readline/readline-6.1.tar.gz
tar xzvf readline-6.1.tar.gz
cd readline-6.1
./configure --prefix=/usr/local
make
sudo make install

Then I read this which saved me a lot of time. It essentially says to install readline via rvm. rvm was already installed in the system and readline got installed by the command.

rvm pkg install readline

Be sure to install the ruby version using the --with-readline-dir option. Like so

rvm reinstall 1.9.2 --with-readline-dir=$rvm_path/usr

Now when you try to install with this line, you might get it installed or you might get some errors like

ld: in /usr/local/lib/libiconv.2.dylib, missing required architecture x86_64 in file

collect2: ld returned 1 exit status

make[1]: *** [../../.ext/x86_64-darwin10.5.0/tcltklib.bundle] Error 1

make: *** [mkmain.sh] Error 1

Well, this means that you might have a wrong dylib file version on the machine.

The first this we need to look at now is whether we have XCode. If you have XCode and the version is 4.2 then you will have to check for this file in

/usr/lib/libiconv.2.dylib

Try to execute a file command on this

file /usr/lib/libiconv.2.dylib 
/usr/lib/libiconv.2.dylib: Mach-O universal binary with 3 architectures
/usr/lib/libiconv.2.dylib (for architecture x86_64): Mach-O 64-bit dynamically linked shared library x86_64 
/usr/lib/libiconv.2.dylib (for architecture i386): Mach-O dynamically linked shared library i386 
/usr/lib/libiconv.2.dylib (for architecture ppc7400): Mach-O dynamically linked shared library ppc

Find the x68_64 and you are in luck !

Just remove the old dylib and link the new one like so :

rm /usr/local/lib/libiconv.2.dylib
ln -s /usr/lib/libiconv.2.dylib /usr/local/lib/libiconv.2.dylib

Now running the rvm install works great !

Kudos !!!

References:
http://hello.keewooi.com/ruby-1-9-3-preview-1-available-now/
http://forums.pragprog.com/forums/148/topics/9975
http://geekyninja.blogspot.de/2010/12/installing-ruby-192-with-rvm.html
http://stackoverflow.com/questions/5426892/trouble-installing-ruby-1-9-2-with-rvm-mac-os-x
http://stackoverflow.com/questions/3703792/ld-symbols-not-found-when-linking
http://stackoverflow.com/questions/7962550/error-installing-ruby-1-9-3
https://rvm.io/packages/readline/
http://stackoverflow.com/questions/8675194/error-installing-1-9-3-with-rvm-on-lion

API accesses

Its great how far technology has advanced in terms of providing access. Now-a-days one gets all the APIs to access any online application. They even document it so precisely and accurately. And if one wants a wrapper for languages like Ruby, Python, Perl and PHP then that is readily available as well.

Well I'm going to shortly discuss about some Gems I have used to access these APIs.

The first Gem that I purely awesome is the 'omniauth' Gem. It has all the routines necessary to build add-ons for other Omniauth Plugins. You might need to read more about oauth to get an idea. I managed to use the plugins - omniauth-twitter, omniauth-facebook, omniauth-linkedin and omniauth-instagram with this Gem. And its so easy.

You will have to add an omniauth.rb file in the initializers for starters.


Rails.application.config.middleware.use OmniAuth::Builder do 
 provider :linkedin, LINKEDIN_CONFIG['api_key'], LINKEDIN_CONFIG['secret_key']   
 provider :twitter, TWITTER_CONFIG['consumer_key'], TWITTER_CONFIG['consumer_secret'] 
 provider :facebook, FACEBOOK_CONFIG['app_id'], FACEBOOK_CONFIG['secret'], :scope => FACEBOOK_CONFIG['scope'], :display => 'popup' 
 provider :instagram, INSTAGRAM_CONFIG['client_id'], INSTAGRAM_CONFIG['client_secret'], :scope => INSTAGRAM_CONFIG['scope'] 
end


It might be a good idea to insert these configuration files on deployment, rather than put them in the git.

The you will have to call something like

current_user.services.create!(
 :provider => auth['provider'], 
 :uid => auth['uid'], 
 :token => (auth['credentials']['token'] rescue nil), 
 :secret => (auth['credentials']['secret'] rescue nil))

Better add in lots of Exception handling.

This is the authorization part. The idea is generally at the end of the authentication, you will get a token which you should use for further requests to these services. To access the data from these services, one would have to use other Gems and then pass the auth_token (and auth_secret).

The gems used to access the data are :
fb_graph Gem for Facebook
twitter Gem for Twitter
linkedin Gem for Linked In
instagram Gem for Instagram

Try them out. You will love them.