Re: Ada Quality and Style book discussion ("_Type" suffix)

[Brian May <bam@snoopy.apana.org.au>]

>>>>> "Georg" == Georg Bauhaus <bauhaus@futureapps.de> writes:

    Georg> Somehow this discussion reminds me of the type prefix notation
    Georg> introduced in some Windows C programming books.

    Georg> lpszLastName;

That is a style that was used, I believe, by Microsoft, in Windows 2
(probably 1.0) days. Its possible it first came from IBM (or
Microsoft?)  in OS/2 1.0 (my memory isn't that good). I believe the
windows include files still use it.

It was decided that it helped if you were reminded what type the
variable is whenever you go to use it. Perhaps overused. I am not sure
there is even a distinction between "long pointers" (lp) and "short
pointers" anymore with 32 bit software (not counting low level device
drivers and OS code), but the names seem to remain. Also, how often do
you encounter a string in C that isn't null terminated (sz)?

Possibly this style was influenced by lack of type safety, especially
in early C compilers.

Also, you could have two variables:
spszLastName
lpszLastName

To signify that one is a short pointer and one is a long pointer to
the same data.

However, sometimes it still helps to add a type prefix/postfix to a
variable, if for example two or more variables contain the some data
but different types for example.

type kilometres_per_hour ...;
type miles_per_hour ...;

....

vehicle_speed_kps := convert(vehicle_speed_mph);

or even:

kps := convert(mph);

Is easier to understand then what I often see happen:

car_speed := convert(vehicle_speed);

What units was car_speed again? What units was vehicle speed? What is
this convert doing? Gee - I need the speed in meters_per_second
too. Lets create a new variable temp_1_car_speed. Now I need to
calculate the "wind speed" of the car (yes - dumb example - I don't
know why you would want to do this, unless the car can fly or drive
over water). temp_2_car_speed. Hang on. This code also works for
trucks, too. Who cares, its just a variable name...

Next month, somebody takes over the code: "This code is a complete
mess - It is going to be much quicker if I just rewrite the code
instead of trying to work out what all of these temp_n_variable do. I
will give better variable names like variable_temp_b instead, and
document everything on this scrap piece of paper. Did anyone see where
I put it?" <grin>.


It is interesting that the decided to remove spaces, and replace make
the next letter uppercase. I don't like this when you have to encode
an abbreviation in the function name:

MakeHtmlForPage

seems wrong, as it is HTML not Html, however, this is worse:

MakeHTMLForPage

Is the abbreviation HTMLF?

Unfortunately, this style seems to be required for CORBA (as
underscore is used for a special purpose in the C bindings).

Enough of my raving.
-- 
Brian May <bam@snoopy.apana.org.au>