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From: 18k11tm001@sneakemail.com (Russ)
Newsgroups: comp.lang.ada
Subject: Re: Ideas for Ada 200X
Date: 30 May 2003 17:49:43 -0700
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Stephen Leake <Stephe.Leake@nasa.gov> wrote in message news:<u4r3co12f.fsf@nasa.gov>...
> 18k11tm001@sneakemail.com (Russ) writes:
> 
> > > Occasionally I run into code that looks something like:
> > > 
> > > production_total( total_class ).shift( shift_index ) :=
> > >   production_total( total_class ).shift( shift_index ) + count;
> > > 
> > > That would read a lot cleaner as:
> > > 
> > >   production_total( total_class ).shift( shift_index ) += count;
> > 
> > Couldn't have said it better myself.
> 
> What is wrong with having a style guide that says:
> 
> "If you have statements like 
>    production_total( total_class ).shift( shift_index ) :=
>       production_total( total_class ).shift( shift_index ) + count;
> 
> you must write an appropriate Increment function, and use it instead"

Because it's one hell of a lot easier, not to mention less
error-prone, to just use +=. That's what Ada is all about.

I don't blame anyone for disliking ++, but += should be your friend.

> Problem solved; no need for language change or compiler support.

Yes, but it's far from the best and simplest solution.

> > And let's not forget that +=, -=, etc. also allow for more efficient
> > in-place vector/matrix operations because they avoid the need for a
> > temporary. If you don't understand this, that's OK, but please don't
> > argue with me because you will be wrong.
> 
> Same argument; a package that provides vector/matrix math must provide
> an appropriate in-place Increment function.
> 
> Ada is about ease of reading, _not_ about ease of writing.

+= improves readability too! Which is clearer,

	A += B

or

	Add(A,B)

The latter doesn't make clear what exactly is being done. Is the
result ending up in A or B? Yes, you can write something that would be
a bit clearer, like

	Add ( Into=>A, Add=>B )

but it still would not be as clear or as elegant as A += B.

In-place operations on a variables are so fundamental that they
deserves their own syntax. If you can't handle that, what kind of
"programmer" are you?