DSL(Domain Specific Language) is a language defined to fulfill some domain specific requirements to ease people's work. It can be used to define attributes and actions of a domain easily and cleanly. And it is often created based on some common observations or micro patterns of some domain.In Ruby world, there are quite a few places people can find DSL. For example, Ruby itself, Chef recipes.To create a class in Ruby, the traditional OOP way would look like.class User @name = nil @email = nil def name @name end def name=(val) @name = val end def email @email end def email=(va...

Security has become a vital concern in most of the online transactions nowadays. Lots of the world's most popular websites have adopted security protocols to transfer data, especially sensitive data. These security protocols including SSL/TLS which are using the private/public key exchange mechanism to establish secure connections. The private/public key cryptography is a really important invention and it allows data to be transferred securely and solves the big problem of transferring symmetric key securely over Internet at the same time. Because of this characteristic, private...

In programming and document editing, we may frequently encounter carriage return and line feed, i.e the well known CRLF.  But do you know about the history and difference of carriage return and line feed?Before computer came out, there was a type of teleprinter called Teletype Model 33. It can print 10 characters each second. But there is one problem with this, after finishing printing each line, it will take 0.2 second to move to next line, which is time of printing 2 characters. If a new character is transferred during this 0.2 second, then this new character will be lost.So scientists ...

Ruby provides ! to change state of some object in place. Hence if you see some functions have ! appended, it means the state of the caller of the function is expected to be changed. This is a very interesting Ruby feature. But sometimes one should be cautious when using this kind of functions because you would get unexpected behavior if using improperly.Let's take an example of String#downcase!. According to the documentation.Downcases the contents of str, returning nil if no changes were made. Note: case replacement is effective only in ASCII region.If there is a String pl...

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