RoR and Text Editors Part-2
More on text editors that are used with RoR and we not discuss VIM or Vi Improved. Vim like Emacs is quite efficient and easy to use with RoR provided it is set-up properly. The nice about Vim is that it has the nifty way of highlighting syntax in ruby making it easy to trace and debug. It features advanced features such as having a selective command and insert mode with the first being the default mode upon startup. It is not a word processor so fonts and other word processor features are not to be expected.
TextPad
One of the quickest and easiest to use as a text editor for making RoR programs with straightforward interface and features mostly adept to windows users. Though considered a text editor it is capable of syntax highlighting, search , spell check and macro recording which makes it a choice of many developers.
ArachnoRuby
Is deployable on both windows based and Unix based systems and is considered to be the native editor of RoR. It was not too user friendly so it quickly lost favor of many developers who turned to the other specified editors for programming code.
Getting Started and how to open Programs : Part 2
Save the text file with the following filename “first1.rb” and we now go into the syntax checking function and the facility provided to show the syntax check verbosely. The following code shows how code is checked for syntax correctness and returns the result of the said checking by typing the following code :
$ ruby :cw first1.rb
The “-c” flag initiates Ruby’s syntax checker while the “w” flag shows the result of the syntax checker. If there is no issue with the code being checked you get a “Syntax OK” result which means you can execute the code for there are no syntax issues. Type $ruby first1.rb on the command line and you get the result ” The concatenated line is : This is my first Ruby Program “
Getting Started and how to open Programs : Part 1
RubyonRails is similar to most programming languages where in one can use the command line in windows or a terminal in Unix based systems. All programs should be written and saves in plain text format for the compiler and interpreter to process it easily. The first program would give you a feel for the overall syntax of how the program is created and what the compiler does. Type the following code into the text file to see how it is done:
#this is a sample program
a = “This is”
b = “my first Ruby Program”
print “The concatenated line is :”
print a << b
The next post would show the continuation of the exercise.
Next step : Creating the database for the filename application
The next phase or step would be to create a database for the application to use. Make sure the MySql engine is running and in the command window type “mysql -u root -p” and press enter and another enter for the password when prompted for there has not been any defined password yet. You are now logged into the engine as the root user and proceed to create the database by entering the following command “create database filename_development”. Also type in “grant all on filename_development.* to ‘ODBC’@'localhost’ this tells windows to grant access to a user named ODBC so you avoid an error when you try to access the said database from the command prompt. We next tackle the creation of tables that would allow the database to store the information we send it.
Database manipulation
The database has been initialized, so now we get down to business of defining the fields in that database and include a field that we would call a foreign key which allows the establishment of the one to many relationship between the tables. This part of the process requires quite a bit of background of database creation, manipulation and handling. It also requires knowledge regarding the workings of data types. So assuming you do not have much knowledge in such areas do some more reading to give you a better understanding of what how and why they are there. The ROR developers might say that it is very easy to do and use ROR but without the background on logic formulation, data types and manipulation as well as database handling the rest of the posts which would tackle ever hardening topics and operations would be very difficult to make sense of.
Don’t get me wrong, we just want to make life easier for you and not have you not understanding anything at all.
Next Step : Creating Empty Applications
Now that all has been set-up and is working, you should be able to create empty apps which is merely defining the application using rails which automatically creates all the necessary directories that are needed. Open a command prompt window and go to the directory where it was installed and proceed into the rails_apps directory. Type in ‘rails filename’ and rails creates all the necessary directories you would be needing for the development process. Don�t get freaked out when you see the multitude of directories for they will be filled out by “RAILS” and not by you manually. The next post will discuss some of the nuances of those dizzying directories to take some of the fog over them out.
Simplifying the previous program with modifiers
As said in the past post, there is an easier way of doing the stuff we did in the last program which would be very helpful when coding thousands of line of code when you do end up building your own programs is ruby.
class BookList
def [](key)
if key.kind_of?(integer)
result = @Books[key]
else
result = @Books.find { |aBooks| key == sBooks.name}
end
return result
end
end
Simplifying the code further by using the ‘if’ statement as a modifier it becomes a shorter easier to attain the same results as with the first program:
class Booklist
def [](key)
return @Books[key] if key.kind_of?(Integer)
return @Books.find { |aBooks| aBooks.name == key }
end
end
The use of the ‘find’ command in Ruby is simply a call to a function that is executed and it can be compared to a block call in many other languages such as Perl, C++ or Java.
Using the ‘yield’ statement
It might be almost similar but relatively different in a big way for blocks may appear only in the source adjacent to a method call which means it should be written on the same line as the method’s last parameter and it is not implemented once it is encountered but, Ruby rather remembers the context by which the block of code appears then enters the method. Within the method itself, the block of code may be called as if it were a block in itself by using the ‘yield’ statement. After the block of code has been executed, control returns immediately right after the call to the yield statement. Sample use of ‘yield’:
def threeTimes
yield
yield
yield
end
threeTimes {puts “Hi There”}
How to Install Ruby on a Shared Web Host
by Chubs
Create a directory for all of the software you are going to download and installed. In this example, the created directory is “temp” at the root of the files system, but you can use any name and location you like.
cd /
mkdir temp
chmod 775 temp
Now, download, configure and install Ruby. You can download the latest stable source tarball for Ruby here. Wget is used in this example:
cd temp
wget ftp://ftp.ruby-lang.org/pub/ruby/ruby-1.8.2.tar.gz
tar -zxvf ruby-1.8.2.tar.gz cd ruby-1.8.2
Specify an install directory since there are times when you won’t have permissions to install things in normal directories. Here, we can see the “configure” script for Ruby, creating a directory inside “/usr/local” for installation:
./configure –prefix=/usr/local/ruby –exec-prefix=/usr/local/ruby
Now, you have a Makefile that you can compile:
make
make install
Your Ruby is now installed. You should try making a symbolic link to Ruby somewhere in your local path:
ln -s /usr/local/ruby/bin/ruby /usr/local/bin/ruby
Hashes : In Layman’s Term
Image Source: codeproject.com
One key feature of Ruby on Rails is Hashes. Now, just try to think of hashes like a PARTY. The party is a potluck occasion, naturally, each guest is required to bring an item or food. You will then need a LIST of all the guests, now this can be managed as an array. But you will also have to make a way to monitor all types of food that is being brought to the event. And to explain it further, you will want to know who is bringing the pasta, who will be bringing the fried chicken and so on. This is where Hashes come in. You will use hash to store value pairs or key pairs, this in turn will enable you to store that particular data. If for example Amanda is the “key”, and she brought cake, the variable stored and accessed by the key will be “cake”.