In Re: Inlining method/function calls?, Zaxo describes using the C preprocessor for macro definitions. All of a sudden, I'm wondering why constant is needed. Could someone tell me why constant is preferable to #define in the following code?

#!/usr/bin/perl -P
 
#define ABC 1
use constant DEF => 1;
 
print ABC, $/;
print DEF, $/;
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$ ./abcd
gcc: file path prefix `/usr/ccs/bin/' never used
1
1
[download]

One thing I'm noticing is that gcc has a warning it throws up. But, wouldn't using the C preprocessor be faster and use less memory than constant, especially for large numbers of them? I'm thinking of sites with mod_perl and a large number of hits ...

Also, what's the difference in using #include vs. require? And, doesn't #define provide first-class macros where there is no real provision for them in Perl?

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