Recently while perusing through, "Design Patterns", I took notice of an interesting naming convention. The authours used the underscore character to represent the member variables of a class.

class Thread
{
    public:
        Thread(unsigned long flags);
       ~Thread();

    private:
        HANDLE    _thread;
        DWORD     _threadid;
};

 

Personally, I find it quite effective and pleasant to use. I''ve found myself switching over from the well used ''m''-underscore (''m_'') convention to just the underscore (_). So what do you guys think of this? Dire Wolf direwolf@digitalfiends.com P.S. Before anyone replies that a variable starting with an underscore is invalid, just let me say that you''d be wrong.

I think it is inconvinient, cause many C functions in standard libraries begins with underscore, and it is bad for public members, cause reference like object._publicmember looks not very good. Thank you.

Novoselov Ilya
nullpointer@chat.ru

Actually, if you follow Design Patterns correctly, and stick to strict Object Oriented principles, then there is no such thing as a public member.


People might not remember what you said, or what you did, but they will always remember how you made them feel.
Mad Keith the V.

Anonymous,

Its very rare to have public data members. Still, to address your point:

object._whatever 

and

object.m_whatever  

Look fine to me. As Mad said, you shouldn''t really be using public data members in user classes. Private implementation classes with public data members are acceptable in some circumstances but in general are not conducive to proper program design.

Just my opinion.

I''d still like to hear some more opinions on the matter.

Dire Wolf
direwolf@digitalfiends.com

I think as long as a convention does not make the code harder to read or maintain then it is plenty fine if it helps to keep track of things.


Corry Trout
ctrout@telusplanet.net

I thought prefixing variables/functions with _ would invade the compiler''s namespace?

That is just plain ugly.

Well that is your opinion and you are entitled to it

NuffSaid,

The underscore does not invade the compiler''s ''namespace''. Microsoft defines the double-underscore as ''reserved'' by the compiler. They recommend that you do not use the underscore character for variable names due to future implementations. This is probably to avoid clashes with reserved words like __stdcall etc.

I''m still debating what I like better:

class Thread{    public:        Thread();       ~Thread();    private:        HANDLE  _threadid;}; 

or

class Thread{    public:        Thread();       ~Thread();    private:        HANDLE  m_threadid;}; 

quote:
P.S. Before anyone replies that a variable starting with an underscore is invalid, just let me say that you''d be wrong.

Well they wouldn''t be totally wrong. Any name, variable or not, starting with an underscore followed by a capital letter or with two consecutive underscores anywhere in the name is invalid i.e. reserved for the implementer (e.g. Microsoft) and the standard.

quote:
This is probably to avoid clashes with reserved words like __stdcall etc

That''s exactly the reason, which is why the new types in C99 have names like _Bool instead of ''bool''

Speaking of which, Wilka, do you know where can I get information on the new data types in C99 like ''_Bool'' and ''long long''?


- Houdini