mirrors/eiffel-org
1
0
Fork 0
mirror of https://github.com/EiffelSoftware/eiffel-org.git synced 2025-12-06 14:52:03 +01:00
Code Issues Packages Projects Releases Wiki Activity

Author:halw

Browse Source 
Date:2008-10-14T22:21:18.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@82 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
This commit is contained in:
halw
2008-10-14 22:21:18 +00:00
parent 7bf0b00d90
commit a7cbdda131
1 changed files with 17 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
documentation/current/method/eiffel-tutorial-et/et-hello-world.wiki
View File

@@ -7,17 +7,17 @@ When discovering any approach to software construction, however ambitious its go
You write a class <code> HELLO </code> with a single procedure, say <code> make </code>, also serving as creation procedure. If you like short texts, here is a minimal version:
<code>
class
HELLO
HELLO
create
make
make
feature
make is
do
print ("Hello World%N")
end
make
do
print ("Hello World%N")
end
end
</code>
@@ -25,23 +25,23 @@ end
In practice, however, the Eiffel style rules suggest a better documented version:
<code>
indexing
description: "Root for trivial system printing a message"
author: "Elizabeth W. Brown"
description: "Root for trivial system printing a message"
author: "Elizabeth W. Brown"
class
HELLO
HELLO
create
make
make
feature
make is
-- Print a simple message.
do
io.put_string ("Hello World")
io.put_new_line
end
make
-- Print a simple message.
do
io.put_string ("Hello World")
io.put_new_line
end
end -- class HELLO
</code>
@@ -56,7 +56,7 @@ The name of the class is <code> HELLO </code>. Any class may contain "features";
The definition of <code> make </code> appears in a <code> feature </code> clause. There may be any number of such clauses (to separate features into logical categories), and each may contain any number of feature declarations. Here we have only one.
The line starting with <code> -- </code> (two hyphen signs) is a comment; more precisely it is a "header comment", which style rules invite software developers to write for every such feature, just after the <code> is </code>. As will be seen in [[8 Design by Contract (tm), Assertions and Exceptions|"The contract form of a class", page 44]] , the tools of EiffelStudio know about this convention and use it to include the header comment in the automatically generated class documentation.
The line starting with <code> -- </code> (two hyphen signs) is a comment; more precisely it is a "header comment", which style rules invite software developers to write for every such feature, just after the feature is named. As will be seen in [[8 Design by Contract (tm), Assertions and Exceptions#The_contract_form_of_a_class|"The contract form of a class"]], the tools of EiffelStudio know about this convention and use it to include the header comment in the automatically generated class documentation.
The body of the feature is introduced by the <code> do </code> keyword and terminated by <code> end </code>. It consists of two output instructions. They both use <code> io </code>, a generally available reference to an object that provides access to standard input and output mechanisms; the notation <code> io </code> . <code> f </code>, for some feature <code> f </code> of the corresponding library class ( <code> STD_FILES </code>), means "apply <code> f </code> to <code> io </code>". Here we use two such features:
* <code> put_string </code> outputs a string, passed as argument, here <code> "Hello World" </code>.