Why are we overusing the preprocessor?

[Phil Edwards]

I don't know why you Cc'd nobody@gcc.gnu.org, or individual people for
that matter...

On Tue, Jan 01, 2002 at 12:04:08PM -0500, Jeffrey Turner wrote:
> In going through stl_algo.h (Wouldn't it be easier to distinguish
> these headers from the std_xxxx.h headers if we called them
> gnu_xxxx.h instead?

stl_* files were imported from the HP/SGI version a few years back.

the std_ files may or may not be going away.

It's not very difficult to distinguish them if you read the documentation.
Renaming files in CVS is enough of a pain that we don't do it very often.


> preprocessor cousins #includes, tend to obfuscate things
> by making one search/grep all over the place to figure out the
> real meaning of a statement.  I know the theory is that brevity
> is a blessing - but, IMHO, not at the expense of clarity.

Have you seen how the constructs are /used/ rather than looking at how
they are /defined/?

When the definition for std::vector<_Tp> starts off with

    __glibcpp_class_requires(_Tp, _SGIAssignableConcept)

I think that's a major win for clarity /and/ brevity.  Try replacing that
with what it expands into -- and don't forget you'll end up with "#ifdef
_GLIBCPP_CONCEPT_CHECKS" everywhere, because the resulting expansion isn't
always active.


The preprocessor is like any other tool or weapon.  Its mere existence
isn't necessarily evil;  how we use it makes it good or bad.  Don't go
ripping out uses that don't have a better replacement.  Or for that matter,
that have no replacement at all.


Phil

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