🚀 go-pugleaf

Trying to explain to a newbie how to do input by whole lines in C++,
the way they easily used to do it with fgets in bad ol' C, I got bit
(besides a bug in the libg++ implementation of getline(), which just
points to some obscurity between the standard libraries' usages of
length/size/capacity for strings -- obscurity enough to confuse the
implementor) by a gotcha in the standard itself:

per paragraph 21.1.1.10.8, "Inserters and extractors", getline()...:

    If    the    function    appends    no    characters,    it    calls
    is.setstate(failbit),    which    may    throw     ios_base::failure

Eep.  So, instead of a smooth, simple and elegant style like...:

	while(getline(cin,mystr)) {
	    // process mystr
	}

one has to adopt a convoluted...:

	while(1) {
	    getline(cin,mystr);
	    if(cin.eof() || cin.bad()) break;
	    if(cin.fail()) { // just an empty line -- darn 21.1.1.10.8!-(
		cin.clear();
	    }
	    // process mystr -- at long last!
	}

Why the gratuitous spec to setstate(failbit), even possibly to throw!,
for something as innocuous as an empty line (i.e., just the terminating
'\n'), which the user could so easily test themselves if it had any
special significance for them...?  I found myself unable to explain
the rationale for this to the newbie -- because I can't see any
myself.  Any chance for a change...?  Or, what am I missing...?


Alex
--
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Email: martelli@cadlab.it                            Phone: +39 (51) 597313
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