Original date:2016-05-24 13:06:17 Edited by: _tom Subject: tutorial Ruby to Euphoria

== Going from Ruby to Euphoria involves learning to think simpler.

Ruby reference: The Book of Ruby H. Collingbourne ( )

"Ruby’s syntax may look simple at first sight but, the more you get to know the language the more you will realize that it is, on the contrary, extremely complex."

Some observations on the differences between Ruby and OpenEuphoria.

Ruby Euphoria
very entity oriented (OOP) not based on entities

They say "object" I say "entity" because we use object as a data-type.

OOP is trendy and popular with many programmers. All OOP languages have the alias problem where a copy does not produce a new unique object. This requires you learn how to clone objects.

Euphoria does not have dot notation.

OOP languages emphasize polymorphism as a way to make code gerenic and versatile. Euphoria is naturally generic so you will find functions that work on strings can work on raw numbers just as nicely.

Extra code to create and then use entities may complicate small programs.

Ruby Euphoria
self-modifiying code possible no self-modifiying code

First, Euphoria is interpreted and apps can be distributed as a "bound" executable. Second, Euphoria can be translated and compiled using C compiler. This close compatibility with "C" means that code is not self-modifying.

Ruby Euphoria
no declarations, inferred types explicit declarations; only three primary data-types

Euphoria has a "no surprise" police; that means no variables become declared or have values assigned in some spontaneous fashion without your explicit intentions. The Ruby NIL value does not magically appear when you forget to assign a value to a variable.

In a array if you output an non existing item you get NIL. In Euphoria you get an error message that the non-existing item does not exist.

That means all variables must be declared. We use atom ( individual value) and sequence (list of values) to show the intended use of a variable. But, you could use object which is the universal data-type.

Note that real, integer, character data-types are all atom.

I feel this "no surprise" policy makes reading Euphoria code easier.

Ruby Euphoria
creative syntax simple pedictable syntax

In Ruby you can, sometimes, leave out parentheses as part of a routine name: print and print() can be the same. In Ruby you can leave out the "then" keyword in a if statement (except when you can't leave it out.) You have one syntax in Euphoria with no shortcuts.

A multiline comment must have start and end markers flush with the left margin. Ruby syntax may follow different rules depending on context. Euphoria is always consistent.

Ruby uses just the "end" keyword to terminate a code block. Euphoria always include the starting keyword name: an "if" statement terminates with "end if". In the case of nested code this makes Euphoria easier to read.

Euphoria syntax is fixed but freeform. You can not leave out keywords, but you can choose the layout , spacing, and line breaks when you write code to suite you personal style.

Ruby Euphoria
use global variables a lot global variables are rare; better to select from export or plublic
fine grained control of scope

See documentation on scope to understand the Euphoria way.

Ruby Euphoria
three styles
"Hello" << " world"
"Hello" + " world"
"Hello" " world"
one style
"Hello" & " world"

Ruby concatentation is tricky. Euphoria concatenation is the same regardless of the items.|

Ruby Euphoria
constant has first letter capitalized use constant keyword, use any valid identifier

Ruby has some specific rules for identifiers.

Ruby Euphoria
special trailing ! added to routines to work around alias problem no alias problem, all routines work the same

A Ruby routine named capitalize! (with !) will modify a string. Routines without the (!) result in a new entity.

Ruby Euphoria
for output need .to_s (to string) methods for string output use puts, for number output use ? or print
Ruby Euphoria
zero based indexing one based indexing
s[1,3] s[2..4]
s[-1] s[$]

Indexing logic in Ruby is different.

given = "Hello" then s[1] is e and s[1,3] is ell (second value is for number of items)


given s = "Hello" then s[2] is e and s[2..4] is ell

All Euphoria index values are postive. Ruby uses negative indexing to count backwards from the end. In Euphoria the $ marks the last itme in a sequence list so that $-1 is the second last item.

Ruby Euphoria
def keyword for function defintions keyword procedure for if no value returned
keyword function if value must be returned

Intent of a routine is explicit and clear form the procedure and function keywords. A function must return a value, however these return values may be ignored.

Ruby Euphoria
creative could use while ... end while loop for almost everything

From my reference, p75, you can write code that looks like

def tired 
   # some code ... 
def snore 
   # some code ... 
def sleep 
    # some code ... 
while tired do sleep end 
while tired 
sleep while tired 
end while tired 

If you think in Ruby this all makes sense.

Euphoria is a lot simpler than Ruby, much less to learn.


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