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Updated wikipage Differences between ETL 2nd printing and Eiffel Software implementation. (Signed-off-by:jocelyn). git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@2162 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
98 lines
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98 lines
4.0 KiB
Plaintext
[[Property:modification_date|Tue, 09 Jul 2019 08:25:22 GMT]]
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[[Property:publication_date|Tue, 09 Jul 2019 08:25:22 GMT]]
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[[Property:title|Differences between ETL 2nd printing and Eiffel Software implementation]]
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[[Property:link_title|ETL 2nd printing vs implementation]]
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[[Property:weight|-9]]
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[[Property:uuid|fc1e73f4-5646-aa41-e7fe-97dc6f3ceb04]]
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{{seealso|See also: [[Differences between standard ECMA-367 and Eiffel Software implementation|Differences between standard ECMA-367 and Eiffel Software implementation]] }}
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"ETL 2nd printing" refers to the book "Eiffel: The Language" (2nd printing), published by Prentice Hall.
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==Added classes==
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* 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]] }}
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==Added classes==
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* 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
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* New <eiffel>TUPLE</eiffel>, <eiffel>ROUTINE</eiffel>, <eiffel>PROCEDURE</eiffel> and <eiffel>FUNCTION</eiffel> classes required by the agent mechanism.
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==Added keywords==
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* <code>Precursor</code>
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* <code>reference</code>: new keyword to specify that a type is used as a reference type.
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* <code> agent</code>: new keyword used by the agent mechanism.
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* <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:
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{|
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|-
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| Old syntax
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| New syntax
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|-
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| !! a
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| <code>create</code> a
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| !! a.make
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| <code>create</code> a.make
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|-
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| !<eiffel>B</eiffel>! a
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| <code>create</code> {<eiffel>B</eiffel>} a
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|-
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| !<eiffel>B</eiffel>! a.make
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| <code>create</code> {<eiffel>B</eiffel>} a.make
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|}
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* <code>note</code>: replacement for the keyword <code>indexing</code>.
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* <code>attribute</code>: new keyword to declare attribute body.
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* <code>attached</code>: new keyword to specify attached types and object tests.
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* <code>detachable</code>: new keyword to specify detachable types.
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==Added semantics==
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* [[ET: Genericity and Arrays|Generic creation]]
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* 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:
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{|
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| Old method
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| New method
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<code>
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local
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a: STRING
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do
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‼ a.make (10)
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f (a)
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end
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</code>
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<code>
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do
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f (create {STRING}.make (10))
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end
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</code>
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|}
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This is also very useful since it can improve the power of assertions.
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* 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.
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* [[ET: Other Mechanisms|Tuples]]
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* [[ET: Agents|Agents]]
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* Feature access: <br/>
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<code>
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local
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value: INTEGER
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do
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value := {MY_CLASS}.value
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end
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</code>
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<br/>
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The previous call is valid, if and only if:
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** <eiffel>value</eiffel> is a feature representing a constant of a basic type (<eiffel>INTEGER</eiffel>, <eiffel>DOUBLE</eiffel> or <eiffel>CHARACTER</eiffel>)
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** <eiffel>value</eiffel> is a C/C++/DLL external feature
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** <eiffel>value</eiffel> is an IL static external feature
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==Added external support==
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Look at the page for [[C externals|C]] and [[C++ Externals|C++]] with the introduction of `struct` and C++ external features encapsulation.
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