What argument names do you prefer in constructors? Suffixes, prefixes or smth else?

Question

For example, I sometimes use "Set" suffix, like that:

ClassA
{
    public:
        ClassA(int xSet, int ySet):
            x(xSet),
            y(ySet)
        {
            ;
        }

    private:
        int x, y;
};

So, is there a better way to write xSet and ySet?

Why not simply use the same name? Use `this->x(x)` to initialize the member. — Hans Passant, Apr 04 '14 at 09:54

score 2 · Answer 1 · answered Apr 04 '14 at 07:54

2

Sometimes people chose to use special suffixes/prefixes for data members to differentiate them from other variables/parameters. Popular naming conventions are:

1) m_ prefix (e.g. m_x);

2) _ suffix (e.g. x_);

I personally prefere x_ because it's less typing.

answered Apr 04 '14 at 07:54

AlexT

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But aren't the underscore prefixes reserved by the compiler? I sometimes used underscore like x_ which resulted in some logic errors, because of writing x instead of x_ or similar. But thanks for the post! Any other ideas? – user3496846 Apr 04 '14 at 08:01
A underscore as first char is reserved, not every underscore anywhere. – deviantfan Apr 04 '14 at 08:23
1

But an underscore at the end is also difficult to read, and should be avoided. Prefixing `m_` or `my` are valid solutions, _if_ you go this route. – James Kanze Apr 04 '14 at 08:35
What does m_ stand for? – user3496846 Apr 04 '14 at 08:39
1

@user3496846 I guess "m" stands for "member" – AlexT Apr 04 '14 at 08:42
@AlexT That may be the origins, but it is actually used as just an arbitrary signal: `m_` means member (and `s_` means static member. – James Kanze Apr 04 '14 at 08:44

score 2 · Answer 2 · answered Apr 04 '14 at 07:57

2

Every project/team/organization follows their own coding guidelines. If you are looking for something to adopt for yourself or your team, a google search for "C/C++ coding guidelines" should give you some useful links to get started.

Where I work, we use underscore (_) as the suffix of class member data. The arguments to constructors are the same names without the underscore.

answered Apr 04 '14 at 07:57

R Sahu

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Yes, this works well to visually distinguish instance vars from local vars. In languages that permit it, I prefer underscore prefix. Neither should be used on public fields aka properties. – david.pfx Apr 04 '14 at 08:05
Alright, I guess underscore is the best as it gets all the support here :) Will check out guidelines, thanks. – user3496846 Apr 04 '14 at 08:37

score 1 · Accepted Answer · answered Apr 04 '14 at 08:43

Well, the obvious answer is to name the parameters for what they are: initialX and initialY (or in setters, newX and newY). Following this logic, the member variables should probably be currentX and currentY—the usual rule is that variable names should be qualified nouns.

Which is all nice in theory. In practice, it seems that the above might be overkill (or a too rigorous application of the theory). At least, every where I've worked, there's been a convention about naming members, so that one can immediately see whether a name is a member or not. Ideally, it shouldn't be necessary, but practically, we don't work in an ideal world. The two most common conventions I've seen are m_ or my as prefixes for the member names (with s_ or our for static members). The other widespread conventions (using an underscore as prefix or suffix) should be avoided, because leading and trailing underscores aren't very visible, and make the code hard to read. (Leading underscores also tend to be used for very special symbols in the implementation, and should be especially avoided.)

What argument names do you prefer in constructors? Suffixes, prefixes or smth else?

3 Answers3