Hello World
class HELLO_WORLD is main is #OUT+"Hello World\n"; end; end;A few remarks:
- Class names are ALL CAPS; this is not only a convention but is enforced by the compiler.
- The method called
mainis the entry point for execution. It may belong to any class, but if this is different fromMAIN, it must be specified as a compiler option. #is the constructor symbol, calling methodcreateof the corresponding class; here it is used for instantiating theOUTclass, which is actually stdout.- The
+operator has been overloaded here to stand for stream append. - Operators such as
+are syntactic sugar for conventionally named method calls:a + bstands fora.plus(b). The usual arithmetic precedence conventions are used to resolve the calling order of methods in complex formulae. - The program layout allows for pre- and post-conditions (not shown here), showing Sather's Eiffel lineage.
Read more about this topic: Sather
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—A. Holley, U.S. womens magazine contributor. The Lily, p. 38 (May 1852)
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