Xref: utzoo comp.lang.modula2:769 comp.lang.misc:1430 comp.lang.c:9258 comp.lang.pascal:804
Path: utzoo!utgpu!water!watmath!watdragon!violet!gjditchfield
From: gjditchfield@violet.waterloo.edu (Glen Ditchfield)
Newsgroups: comp.lang.modula2,comp.lang.misc,comp.lang.c,comp.lang.pascal
Subject: Re: Modula2's godawful IO.
Message-ID: <6366@watdragon.waterloo.edu>
Date: 13 Apr 88 13:50:24 GMT
References: <764@ndsuvax.UUCP> <535@m10ux.UUCP> <96@lzaz.ATT.COM> <547@m10ux.UUCP>
Sender: daemon@watdragon.waterloo.edu
Reply-To: gjditchfield@violet.waterloo.edu (Glen Ditchfield)
Organization: U. of Waterloo, Ontario
Lines: 24

In article <547@m10ux.UUCP> rgr@m10ux.UUCP (Duke Robillard) writes:
>In article <96@lzaz.ATT.COM> bds@lzaz.ATT.COM (BRUCE SZABLAK) writes:
>>I like C++'s overloading of the << and >> operator's even better than
>>printf. It allows you to define custom print routines for each structure
>>(class) declared, and then to print (to stdout for example) you do:
>>	cout << god_awful_structure_instance;
>
>Yeah, but that doesn't help me print out an error message, two strings,
>and an integer return code.  I don't want to have to write a method
>for every print....

Neither would I.  Fortunately for us, the i/o operators can be chained.
	cout << "Error: file " << fname << ", line " << lnum
	     << error_msg << "\n";
I think this is a big improvement over calls to overloaded "Print" procedures.

Details: "<<" associates left-to-right.  `cout << "Error: file "' returns
cout as it's value, which is used as the left operand by `<< fname'.  When
streams like cout (or the standard input, "cin") are used in an integer
context, the stream-to-int conversion returns the stream's status, so you
can write input loops like
	while ( cin >> val ) { ...
If a programmer-defined type must be read or written, the programmer writes
"<<" and ">>" operators for it.