Re: Microsoft style:

From:
"David Webber" <dave@musical-dot-demon-dot-co.uk>
Newsgroups:
microsoft.public.vc.mfc
Date:
Sat, 2 Apr 2011 21:00:38 +0100
Message-ID:
<RfLlp.7780$5t2.4812@newsfe06.ams2>
"Joseph M. Newcomer" wrote in message
news:am6cp6h7bg4d7gn8rd7id64smq62lbgr5c@4ax.com...

All very well till you accidentally define a local variable called 'date'
in
a member function.

****
This is not possibly a problem

typedef struct {
      DWORD date;
} THING;

void SomeFunc(THING & t)
    {
     DWORD date;
     date = t.date;
     ...do stuff to date variable
     t.date = date;
    }

Note that I had exactly *one* abstraction here, "date", which is referred to
by the name
"date" everywhere it is used.

----

Yes I can do that too, but I prefer not to as different names are clearer.

----
You can argue that m_date for a member variable makes sense so you can write

void THING::SetDate(DWORD date)
    {
     m_date = date;
    }

but that is a consistent concept if you use it correctly. But writing
    thng_date = date;
in one piece of code and
     whatever_date = date;
for another class makes no sense.
-----

Well if they're that strongly related, you can derive one from the other and
there's then only one. And if they're not, then I don't mind them having
different names. One is the 'date of the thing' the other the 'date of the
whatever'.

-----
  Particularly if there are weird abbreviations like
      thng_date = date;
      wht_date = date;
then the weird abbreviations add one more level of complexity to the
understanding,
-----

Where it isn't obvious I have even been known to write THING::thng_date
within a member function of THING :-)
These days I don't do it often, as it usually points to the idea that a
clearer nomenclature would be better.

----

whereas

      m_date = date;
has a single, uniform concept everywhere.<
----

I guesss m_ means member. My system just makes a bit more information
explicit - what it's a member of.

I still use m_ for members of CDialog-derived classes though: just out of
bad habit acquired from Microsoft :-)

----

It's the same reason we have function overloading so we can have

    void DoSomething(char *);
    void DoSomething(int);
    void DoSomething(double);<
----

Well that's slightly different (and I do it a lot). These are members of
the same class - my different prefixes distinguish members of different
classes.

----
[Note that the insanity where some APIs are using "Rgn" and some APIs are
using "Region"
is also avoided; is it "Double" or "Dbl"?]
---

Yes I try to avoid that as it makes searching for things easier if you're
consistent.

More later.

Dave

-- David Webber
Mozart Music Software
http://www.mozart.co.uk
For discussion and support see
http://www.mozart.co.uk/mozartists/mailinglist.htm

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