[[Property:modification_date|Mon, 29 Jul 2019 05:54:09 GMT]] [[Property:publication_date|Tue, 09 Jul 2019 08:25:22 GMT]] [[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: INTEGER_8, INTEGER_16, INTEGER_64, CHARACTER_32. INTEGER, CHARACTER, REAL, DOUBLE are aliases to INTEGER_32, CHARACTER_8, REAL_32, REAL_64. {{seealso|[[Differences between standard ECMA-367 and Eiffel Software implementation|Differences between standard ECMA-367 and Eiffel Software implementation]]}} * New TUPLE, ROUTINE, PROCEDURE, FUNCTION, PREDICATE classes required by the agent mechanism. ==Added keywords== * Precursor * reference (now obsolete): a keyword to specify that a type is used as a reference type. * agent: a keyword used by the agent mechanism. * create: Instead of using the famous exclamation mark to create an instance of a class, you can use the keyword create. 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 `!! a` => new syntax `create a` ** Old syntax `!! a.make` => new syntax `create a.make` ** Old syntax `!B! a` => new syntax `create {B} a` ** Old syntax `!B! a.make` => new syntax `create {B} a.make` * note: replacement for the keyword indexing. * attribute: a keyword to declare attribute body. * attached: a keyword to specify attached types and object tests. * detachable: a 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:


local
	a: STRING
do
	‼ a.make (10)
	f (a)
end

** 'New method:


do
	f (create {STRING}.make (10))
end

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:


local
	value: INTEGER
do
	value := {MY_CLASS}.value
end

The previous call is valid, if and only if: ** value is a feature representing a constant of a basic type (INTEGER, DOUBLE or CHARACTER) ** value is a C/C++/DLL external feature ** value is an IL static external feature ==Obsolete constructs== * Explicit values should be used to specify constant attributes instead of keyword `unique`. ==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.