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Subject: Re: [boost] [system][filesystem v3] Question about error_code arguments
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-10-27 09:26:58

Peter Foelsche wrote:
> "Stewart, Robert" <Robert.Stewart_at_[hidden]> wrote in message
> news:DF2E67F3D097004694C8428C70A3FD69046934E01F_at_msgbal516.ds.s
> > As Scott McMurray noted, the call doesn't transfer
> > ownership and isn't
> > polymorphic. However, using a null
> > pointer to indicate the absence of something is idiomatic
> > as Peter Dimov
> > noted. From a purely esthetic point of
> > view, I prefer not having to take the address of the
> > error_code to call
> > such a function.
> How does having to pass an address screw up your esthetic
> view of the code?

Have you looked at the definition of (a)esthetic? It is based upon one's notions of beauty, etc. I dislike putting the "&" wart in front of a variable when calling a function versus the "cleanliness" of not. It isn't as if I was saying doing so was wrong. I just like avoiding it when it isn't needful.

> I usually try to avoid non-constant references in my own
> code, since they are obfuscating the code.

I recognize that deficiency of non-const references, but even when taking the address of something, it isn't clear whether the caller's object will be changed or the function merely allows for a value's absence (using a null pointer). Both approaches require knowledge of the function's signature, at least, to understand the effects on the arguments, so neither is superior in this regard.

> I prefer the clarity of using the address operator to tell the person
> reading the code, what is happening.

All that does -- at the call site -- is indicate that the function takes a pointer. Whether the caller's object is modified, the argument is optional, or both is not indicated. There is no additional clarity over references.

I prefer to use raw pointers to make an argument optional, smart pointers to transfer or otherwise control ownership, and references for all else. You have other ideas. It's aesthetics.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer, Core Software using std::disclaimer;
Susquehanna International Group, LLP

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