Re: auto_ptr problems

From:
Nick Keighley <nick_keighley_nospam@hotmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 28 Mar 2008 09:44:41 -0700 (PDT)
Message-ID:
<a4e49fb1-7ead-4d56-919a-e1e0f49ad541@e6g2000prf.googlegroups.com>
On 28 Mar, 15:11, lbonaf...@yahoo.com wrote:

On Mar 28, 9:20 am, Nick Keighley <nick_keighley_nos...@hotmail.com>
wrote:

I copy pasted this code from one of my projects to another. (I know
it should be a template, but I figure if I can't get the non-template
version there is no point in making things more complicated)

void Symbol_table::insert (const std::string name, const T* type)
{
    std::auto_ptr <const T> ap_type (type); // <-- error =

here!

    // more code...

}

This worked with one value for T but when I changed it. I got a syntax
error


Post the code that works and the code that fails.


rather long I'm afraid

Symbol_table_ok compiles
Symbol_table_fail doesn't

the problem seems to be the declaration of TfailPtr

<code begin>

#ifdef _MSC_VER
// Microsoft compiler
// disable warning: "identifier was truncated to '255' characters in
the debug information"
#pragma warning (disable:4786)
#endif

#include <string>
#include <memory>
#include <map>

class Tok
{
public:
    Tok (std::string name)
        :name_(name), special_(false)
    {}

    virtual ~Tok()
    {}

private:
    std::string name_;
    bool special_;
};

class Tfail
{
public:
    Tfail ()
    {}

    virtual ~Tfail ()
    {}

    virtual void execute (std::ostream&) = 0;
};

typedef std::auto_ptr<Tfail> TfailPtr; // <--- removing this
"fixes" the bug

typedef std::map<std::string,const Tok*> Table_ok;

class Symbol_table_ok
{
public:
    Symbol_table_ok ();
    ~Symbol_table_ok ();

    void insert (const std::string name, const Tok* type);

private:
    Table_ok table_;
};

typedef std::map<std::string,const Tfail*> Table_fail;

class Symbol_table_fail
{
public:
    Symbol_table_fail ();
    ~Symbol_table_fail ();

    void insert (const std::string name, const Tfail* type);

private:
    Table_fail table_;
};

Symbol_table_ok::Symbol_table_ok():
    table_()
{
}

Symbol_table_ok::~Symbol_table_ok()
{
}

void Symbol_table_ok::insert (const std::string name, const Tok* type)
{
    std::auto_ptr <const Tok> ap_type (type);}

Symbol_table_fail::Symbol_table_fail():
    table_()
{
}

Symbol_table_fail::~Symbol_table_fail()
{
}

void Symbol_table_fail::insert (const std::string name, const Tfail*
type)
{
    std::auto_ptr <const Tfail> ap_type (type); // <-- syntax
error here!
}

int main ()
{
    Symbol_table_ok symtab_ok;
    Symbol_table_fail symtab_fail;
    return 0;
}

<code end>

--
Nick Keighley

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