Re: allocate memory in constructor

From:
pjb@informatimago.com (Pascal J. Bourguignon)
Newsgroups:
comp.lang.c++
Date:
Thu, 18 Jun 2009 17:16:47 +0200
Message-ID:
<7ck539wp0g.fsf@pbourguignon.anevia.com>
"bint" <bint@igs.com> writes:

  I have a constructor for a class, it allocates some memory. If the
allocate fails, is there any way to invalidate the object? Ie so that the
call to new <classname> returns nil?


class IdoNotLikeRAII {
protected:
    bool valid;
    int* memory;
public:
    IdoNotLikeRAII(){
        memory=allocate_some_memory_some_way(sizeof(int));
        valid=(memory!=0); }
    virtual ~IdoNotLikeRAII(){
        if(valid){
            deallocate_some_memory_some_way(memory); }}
    virtual bool isValid(){ return valid; }
    virual void doSomething(){
        if(valid){
            doReallySomething(); }}
};

int main(){
    IdoNotLikeRAII* iDontLikeAutoObjectsEither=new IdoNotLikeRAII();
    try{
        if(iDontLikeAutoObjectsEither->isValid()){
            iDontLikeAutoObjectsEither->doSomething();
            // ...
        }
    }catch(...){
        // ...
    }
    delete iDontLikeAutoObjectsEither;
    return(0);
}

--
__Pascal Bourguignon__

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