🚀 go-pugleaf

In article <4eb5r1$b04@news.tuwien.ac.at> schwarz@mips.complang.tuwien.ac.at (Konrad Schwarz) writes:
>I was surprised to learn that constant pointer expressions are
>not allowed in case labels and that the expression in a switch statement
>must be an integral type.  (The reason for the exclusion of floating point
>is obvious to me).  I am interested in the technical reasons for this.

Well, the practical reason is that C compilers have traditionally
disallowed it and nobody made a convincing case for changing this. 

The technical reason for disallowing it is that doing even a vaguely
clever implementation of switch requires knowing the values of the case
labels at compile time.  The values of pointer expressions are typically
not known until link time; on systems using dynamic linking, they may not
be known until run time.  When the values are not known at compile time,
it's hard to implement the switch as anything other than a series of
ifs... and there is no point in writing that as a switch.
-- 
Space will not be opened by always                 |       Henry Spencer
leaving it to another generation.   --Bill Gaubatz |   henry@zoo.toronto.edu