This is fundamentally what a for loop does. It initializes in some way (usually a variable) and loops while a certain condition is true, performing some action after each time through the loop.

Here are some benchmark results to peruse...

Benchmark: timing 100000 iterations of Deparses, for...
  Deparsed:  5 wallclock secs ( 4.43 usr +  0.00 sys =  4.43 CPU)
       for:  6 wallclock secs ( 4.39 usr +  0.00 sys =  4.39 CPU)
[download]

Not too surprising (in fact, I would have been shocked had there really been a substantial difference).

Just thinking of really low-level code, the Deparse version is really just the "under-the-hood" action of a for loop. Think about assembly (pseudo) code:

# Warning: I make no claims to know assembly, this is an example only 
+:-)
mov bx 0    ; Initialize our loop variable
mov ax, 10    ; Remember our exit condition
top:        ; Mark the top of the loop
jnle last:    ; Quit if bx is not less than ax
print bx    ; Do the body of the loop
add bx 1    ; Add one to the loop variable
jmp top:    ; go to the top of the loop
last:
[download]

So, the Deparsed code is just a closer representation of the low-level code.

The continue block (from perlsyn)

If there is a continue BLOCK, it is always executed just before the conditional is about to be evaluated again, just like the third part of a for loop in C. Thus it can be used to increment a loop variable, even when the loop has been continued via the next statement (which is similar to the C continue statement).

So, the continue block executes once per iteration of the loop. Why would you use one yourself?

• Maybe you want a complex "once-per-loop" construct which would be too obfuscated as part of the normal for construct.
• Maybe you want multiple exit points from the body of your loop. You don't want to write the once-per-loop over and over (once per exit point), so put it in a continue, and just use next when you need to exit.
• Maybe you really embrace TMTOWTDI

Russ
Brainbench 'Most Valuable Professional' for Perl

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