[Swan-dev] Add -std=c99 to the compiler flags?

D. Hugh Redelmeier hugh at mimosa.com
Thu Feb 5 21:46:55 EET 2015

| From: Lennart Sorensen <lsorense at csclub.uwaterloo.ca>

| On Thu, Feb 05, 2015 at 01:13:49AM -0500, D. Hugh Redelmeier wrote:
| > Really?  Seems like a no-brainer if you accept the goal of minimizing
| > undefined variable errors.
| I agree, but I have heard people argue that all variables should be
| declared first.  Probably just old fashioned C coders.

Readability is very important.  The reader and the writer of code have to 
follow conventions: "all that's legal" C can be very hard to read 

There is no single obviously best style (except for mine).  Following
any single OK style is a win.

At the moment, Pluto has (almost) all its block scope
declarations at the start of the block, segregated from statements by
a blank line.  That makes it fairly easy to find a declaration: look
to the start of each enclosing block.

Using this "new" capability of mixing declarations and statements can
make this search a little more difficult.

On the other hand, understanding the data-flow and control flow
involving a variable is improved if the scope is shrunk and also if
there is no point in which the variable is uninitialized.

Style suggestions:

- an initializing declaration is preferred to a non-initializing one
  (but don't initialize to a value that will never be used)

- put the declarations in such a way as to minimize scope

- if the lifetime of a variable can be partitioned in such a way that
  the value doesn't carry between partitions, break that into multiple
  variables, one per partition

Declaring the index variable within the for statement looks like a
very good application of these principles

I wonder if there are good ways of making declarations visually stand
out.  Perhaps it is a non-problem, but surely it is the point of the
other side of this argument.

| I love when the compiler spots errors at compile time.


Unfortunately it sometimes takes a guru to understand what a C
compiler is complaining about with type mismatches.  Still, I think
that is learning curve worth climbing.

I guess it takes even more expertise (and good taste) to create these
types.  Of course that's part of what I find rewarding about
programming: the quest for elegance.

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