[[Property:title|Differences between ETL 2nd printing and  Eiffel Software  implementation]]
[[Property:link_title|ETL 2nd printing vs implementation]]
[[Property:weight|-9]]
[[Property:uuid|fc1e73f4-5646-aa41-e7fe-97dc6f3ceb04]]
{{seealso|See also: [[Differences between standard ECMA-367 and Eiffel Software implementation|Differences between standard ECMA-367 and Eiffel Software implementation]]  }}

"ETL 2nd printing" refers to the book "Eiffel: The Language" (2nd printing), published by Prentice Hall.

==Added classes==
* New basic classes have been added: <eiffel>INTEGER_8</eiffel>, <eiffel>INTEGER_16</eiffel>, <eiffel>INTEGER_64</eiffel> and <eiffel>WIDE_CHARACTER</eiffel>.{{seealso|[[Differences between standard ECMA-367 and Eiffel Software implementation|Differences between standard ECMA-367 and Eiffel Software implementation]]  }}

==Added classes==
* New basic classes have been added: <eiffel>INTEGER_8</eiffel>, <eiffel>INTEGER_16</eiffel>, <eiffel>INTEGER_64</eiffel> and <eiffel>WIDE_CHARACTER</eiffel>. <eiffel>INTEGER</eiffel> is now specified as having a 32 bits representation
* New <eiffel>TUPLE</eiffel>, <eiffel>ROUTINE</eiffel>, <eiffel>PROCEDURE</eiffel> and <eiffel>FUNCTION</eiffel> classes required by the agent mechanism.

==Added keywords==
* <code>Precursor</code>
* <code>reference</code>: new keyword to specify that a type is used as a reference type.
*  <code> agent</code>: new keyword used by the agent mechanism.
* <code>create</code>: Instead of using the famous exclamation mark to create an instance of a class, you can use the keyword <code>create</code>. Below you will find a correspondence table between the old and the new syntaxes. The old syntax is still valid, but at some points Eiffel Software will remove it from its implementation: 
{| 
|- 
| Old syntax
| New syntax
|- 
| !! a
| <code>create</code> a
|- 
| !! a.make
| <code>create</code> a.make
|- 
| !<eiffel>B</eiffel>! a
| <code>create</code> {<eiffel>B</eiffel>} a
|- 
| !<eiffel>B</eiffel>! a.make
| <code>create</code> {<eiffel>B</eiffel>} a.make
|}
*  <code>note</code>: replacement for the keyword <code>indexing</code>.
*  <code>attribute</code>: new keyword to declare attribute body.
*  <code>attached</code>: new keyword to specify attached types and object tests.
*  <code>detachable</code>: new keyword to specify detachable types.


==Added semantics==
*  [[ET: Genericity and Arrays|Generic creation]]  
* Expression creation: you can now create an object within an expression. For example, you want to create an object and pass it as an argument to a function. Whereas you had to create a local variable, create the object and pass it to the function, you now simply need to pass to the function the creation expression. Here is a small example: 
{| 
|- 
| Old method
| New method
|- 
| 
<code>
local
	a: STRING
do
	!! a.make (10)
	f (a)
end
</code>

| 
<code>
do
	f (create {STRING}.make (10))
end
</code>

|}
This is also very useful since it can improve the power of assertions. 
* Mutually recursive constraints: one can now write class A [H, G->H] or class B [H -> C, G -> ARRAY [H]]. As a result, the declaration A [D, E] is valid only if E is a descendant of D. Similarly, the declaration B [E, ARRAY [D]] is not valid, if E is a descendant of D.
*  [[ET: Other Mechanisms|Tuples]]  
*  [[ET: Agents|Agents]]  
* Feature access: <br/>
<code>
local
	value: INTEGER
do
	value := {MY_CLASS}.value
end
</code>
<br/>
The previous call is valid, if and only if: 
**  <eiffel>value</eiffel> is a feature representing a constant of a basic type (<eiffel>INTEGER</eiffel>, <eiffel>DOUBLE</eiffel> or <eiffel>CHARACTER</eiffel>)
**  <eiffel>value</eiffel> is a C/C++/DLL external feature 
**  <eiffel>value</eiffel> is an IL static external feature 


==Added external support==

Look at the page for [[C externals|C]]  and [[C++ Externals|C++]]  with the introduction of `struct` and C++ external features encapsulation.