An interesting critical comparison can be found here.
C++ FQA io
Not exactly polite, but makes to think...
Disclaimer
The C++ FQA (that is a critical response to the C++ FAQ) is often considered by the C++ community a "stupid joke issued by a silly guy the even don't understand what C++ is or wants to be"(cit. from the FQA itself).
These kind of argumentation are often used to flame (or escape from) religion battles between C++ believers, Others languages believers or language atheists each in his own humble opinion convinced to be in something superior to the other.
I'm not interested in such battles, I just like to stimulate critical reasoning about the pros and cons argumentation. The C++ FQA -in this sens- has the advantage to place both the FQA and the FAQ one over the other, allowing an immediate comparison. And that the only reason why I referenced it.
Following TonyD comments, below (tanks for them, I makes me clear my intention need a clarification...), it must be noted that the OP is not just discussing the <<
and >>
(I just talk about them in my comments just for brevity) but the entire function-set that makes up the I/O model of C and C++.
With this idea in mind, think also to other "imperative" languages (Java, Python, D ...) and you'll see they are all more conformant to the C model than C++. Sometimes making it even type safe (what the C model is not, and that's its major drawback).
What my point is all about
At the time C++ came along as mainstream (1996 or so) the <iostream.h>
library (note the ".h": pre-ISO) was in a language where templates where not yet fully available, and, essentially, no type-safe support for varadic functions (we have to wait until C++11 to get them), but with type-safe overloaded functions.
The idea of oveloading <<
retuning it's first parameter over and over is -in fact- a way to chain a variable set of arguments using only a binary function, that can be overload in a type-safe manner. That idea extends to whatever "state management function" (like width()
or precision()
) through manipulators (like setw
) appear as a natural consequence. This points -despite of what you may thing to the FQA author- are real facts. And is also a matter of fact that FQA is the only site I found that talks about it.
That said, years later, when the D language was designed starting offering varadic templates, the writef
function was added in the D standard library providing a printf
-like syntax, but also being perfectly type-safe. (see here)
Nowadays C++11 also have varadic templates ... so the same approach can be putted in place just in the same way.
Moral of the story
Both C++ and C io models appear "outdated" respect to a modern programming style.
C retain speed, C++ type safety and a "more flexible abstraction for localization" (but I wonder how many C++ programmers are in the world that are aware of locales and facets...) at a runtime-cost (jut track with a debugger the << of a number, going through stream, buffer locale and facet ... and all the related virtual functions!).
The C model, is also easily extensible to parametric messages (the one the order of the parameters depends on the localization of the text they are in) with format strings like
@1%d @2%i allowing scrpting like "text @2%i text @1%d ..."
The C++ model has no concept of "format string": the parameter order is fixed and itermixed with the text.
But C++11 varadic templates can be used to provide a support that:
- can offer both compile-time and run-time locale selection
- can offer both compile-time and run-time parametric order
- can offer compile-time parameter type safety
- ... all using a simple format string methodology.
Is it time to standardize a new C++ i/o model ?