Re: complex number API

[James Theiler <jt@nis.lanl.gov>]

On Mon, 8 Feb 1999, Mark Galassi wrote:

] 
]     Gerard> I would like to add another form as well, of the suggested
]     Gerard> 'return z' type, since that looks like it would be nicer
]     Gerard> to type.  I'm thinking something contructor-like
] 
]     Gerard> GSL_COMPLEX(x,y)
] 
]     Gerard> which could be used like
] 
]     Gerard> gsl_complex foo_z = GSL_COMPLEX(x,y);
] 
]     Gerard> Trivial as an inline function, but is it possible to do as
]     Gerard> a macro too?
] 
] I would also like such a function, but I can't figure out how to do it
] with a macro.  James's cute trick of using the do { stuff } while(0)
] won't work if you have to return a value.  You do need a block to
] allocate a variable for the result, but I don't know how to return
] something.
] 
] James, do you have any cute tricks?
] 
] Maybe we could go with an autoconf/ifdef-ed use of GCC's inline
] functions across module boundaries, but they are a bit annoying.
] 

Sorry, no cute tricks.

Is this the kind of thing that is likely to be deep in an inner loop,
though? ie, does the macro really buy you that much?

I agree that the following code snippet is annoying
   #ifdef HAVE_INLINE
   inline
   #endif
   gsl_complex func()

but I thought that autoconf was smarter than that, and if you asked
it to check for whether your compiler supported inline's, and your
compiler doesn't, then it would set
   #define inline
in the config.h file.  In that case, can't you blithely write
   inline gsl_complex func()
and the compiler (actually cpp, I guess) will do the right thing?
Maybe I'm wrong...

By the way, I'm not necessarily advocating this for gsl, but i noticed on
another project if i named all my new data types things that ended in _t,
eg "Complex_t", then emacs would color them as if they were builtin types. 
it also made it a little easier to avoid confusion about variable names
and type names.  

regards,
jt

---------------------------------------------
James Theiler                     jt@lanl.gov
MS-D436, NIS-2, LANL        tel: 505/665-5682
Los Alamos, NM 87545        fax: 505/665-4414
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