Re: Having trouble with streams....

From:
Pete Becker <pete@versatilecoding.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 10 Aug 2009 15:49:49 -0400
Message-ID:
<h66dnYrMRu9D5B3XnZ2dnUVZ_s6dnZ2d@giganews.com>
joseph cook wrote:

On Aug 10, 1:05 pm, SpreadTooThin <bjobrie...@gmail.com> wrote:

This constructor is causing the application to crash on Mac OS X, in
xcode...

dbgFile::dbgFile(void) : std::ostream(0), output_buffer(),
indent_buffer(&output_buffer), isopen(false) {}

here is part of the class definition:
class dbgFile : public std::ostream {
private:
    std::filebuf output_buffer;
    dbgBuf indent_buffer;
    std::stack<std::string> s;
    int stack_level;
    bool isopen;

}

I suspect that std::ostream(0) is the culprit, but not sure how to
tell...


A debugger would tell you.

Why are you initializing the ostream with 0? Don't you want it
default-constructed?


basic_ostream doesn't have a default constructor. Its only constructor
(in C++03) takes a pointer to a streambuf. Passing a null pointer is,
indeed, a coding error.

Be careful inheriting from std::ostream. You can't try and use this
class polymorphically.


Um, std::basic_ostream (ostream is basic_ostream<char>) is the base
class for all the standard library's stream types. It's intended to be
used as a base class for all stream types, including user-defined ones.

You haven't posted enough code to be able to say what is the first
thing crashing your code.


Well, maybe. But initializing an ostream subobject with a null pointer
is certainly not a good thing to do.

--
   Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of
"The Standard C++ Library Extensions: a Tutorial and Reference"
(www.petebecker.com/tr1book)

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