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148 lines
6 KiB
Text
148 lines
6 KiB
Text
2.2.3..2 "It is strongly advised": Avoid passive voice. Better "We
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strongly advise you". The editorial/royal "we" is quite acceptable in
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a single-author document of technical nature, and especially in one
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like this with many contributors.
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Either after 2.3 or 2.4 (probably the latter) I think it would be wise
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to insert a warning. Here's a suggested text. I'm putting in a cite to
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my book only because as far as I know nobody else has written down the kind
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of warning that would be useful here in as much detail as I have,
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The Peril of "C++ Disease"
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Like C++ itself, object-oriented programming has sometimes been
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oversold by its proponents. Objects are not a magic bullet for the
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problem of code complexity, and spaghetti inheritence is not an
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improvement on spaghetti code. And, unfortunately, there is some
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evidence that C++ particularly tends to lead programmers into
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coding overcomplex and rigidly cross-dependent classes.
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For a discussion of the general problem, see the discussion of
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"Unix and Object-Oriented Languages" in Eric S. Raymond's "The Art
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of Unix Programming"; you can read it on the Web at
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<http://www.catb.org/esr/writings/taoup/html/unix_and_oo.html>. The
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same book has a more specific critique of C++ which you can read here:
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<http://www.catb.org/esr/writings/taoup/html/ch14s04.html#cc_language>.
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Raymond builds on work by Les Hatton and other to suggest that the
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baroqueness of C++ makes projects written in it especially
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vulnerable to overcomplexity.
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You may be able to prevent "C++ disease" on your project by being
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careful and minimalist in your use of the language. Don't use
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advanced features of the language just because you can. Instead,
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always ask if doing so increases or decreases the readability
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and maintainability of the code. Also, be wary of class
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hierarchies that embody fancy programming patterns at the cost
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of composing classes so tightly to each other that they effectively
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become one large lump, defeating the very purpose of class encapsulation.
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The second cite to tAOUP points at the place where I cited "C++
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Annotations".
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3.3.1 "In this section the type bool is introduced." It is probably
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worth noting here that bool was backported to C in C99.
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Chapter 4:
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You should give this a good going-over to get rid of passive voice.
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Chapter 5:
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5.4.3 "In order to write information to memory, using the stream
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facilities, ostringstream objects can be used." Get rid of passive
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voice. "To write information to memory using the stream facilities,
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use ostringstream."
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5.5.3: You need more passive-voice fixes here.
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Chapter 12:
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Introduction "If the data elements of containers are pointers, the
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data pointed to by these pointers will not be destroyed, resulting in
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a memory leak." This and other problems noted elsewhere in the
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Annotations suggest a general rule: Don't use C pointers!
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This observation should probably go with "Don't use malloc and free"
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in a warning section at the end of chapter 2. Here is a proposed text:
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C practices to leave behind
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C++ tries to hide and semi-automate the details of memory management
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in objects as much as is possible in a statically compiled language.
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It also tries to be upward-compatible with C, notably by supporting
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C-style pointers.
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Unfortunately, these goals are fundamentally incompatible. C-style
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pointers create referential links among objects that C++'s object
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facilities won't know how to manage properly. In later chapters
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we'll describe a lot of specific places this can get you into trouble,
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causing memory leaks and dangling pointers and lots of subtle, nasty bugs.
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Two simple rules of thumb will help you avoid all these problems:
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* Don't use C pointers. Instwed, instantiate objects and pass them
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by reference.
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* Don't use malloc/realloc/free. Use object creation, new, and delete
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instead.
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In some cases, C pointers can be replaced with the STL auto_ptr
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type, which we'll cover in Chapter 17.
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12.3.2: "Actually, in my experience, lists aren't that useful at all,
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and often an implementation will be faster when a vector, maybe
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containing holes, is used." "at all" is unnecessary and can be dropped.
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I would actually recommend promoting that observation out of its
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context and reworking the beginning of 12.3,2. Suggested text:
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12.3.2: The `list' container
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The list container implements a classic linked-list data structure.
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It is a bit of a historical relic left over from a time when machines
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were much slower and more memory-constrained. While it may still
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occasionally be useful (say, in embedded systems for lists with a very
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stereotyped and non-random access pattern) modern practice favors the
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more flexible vector type (among other things, vectors are contiguous
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spans of memory that make better use of cache locality). You should
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know that the list container exists, but use cases for it will be
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rare (we do discuss them towards the end of this section).
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Before list containers can be used the following preprocessor
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directive must have been specified:
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12.3.6: "The map class implements a (sorted) associative array." Add:
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"Python and Perl programmers can think of this as a type-checked analogue
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of the dictionary features in those languages, and it has many of
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the same uses."
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Chapter 14:
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14.5 "The possibilities of C++'s run-time type identification are
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limited compared to languages like Java.": Add "or Python".
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14.5.2 "Actually, the typeid operator returns an object of type
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type_info, which may, e.g., be compared to other type_info
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objects.": Add "This is closely analogous to, e.g., the "type()"
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function in Python."
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Chapter 15:
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This probably needs at its head a reiteration of the warning that
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using C pointers at all in C++ is a bad idea, likely to lead to memory
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leaks if deallocation isn't handled wit extra care and thus best avoided.
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Has nothing to do with `C pointers': no allocation takes place here.
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