On 18/07/12 01:46, Andrew Cooper wrote:
On 17/07/2012 19:36, Lipska the Kat wrote:
On 17/07/12 19:18, Mark Lawrence wrote:
On 17/07/2012 18:29, Ethan Furman wrote:
Terry Reedy wrote:
On 7/17/2012 10:23 AM, Lipska the Kat wrote:
snip
Take for example a Linux system call handler. The general form looks a
little like (substituting C for python style pseudocode)
if not (you are permitted to do this):
return -EPERM
if not (you've given me some valid data):
return -EFAULT
if not (you've given me some sensible data):
return -EINVAL
return actually_try_to_do_something_with(data)
How would you program this sort of logic with a single return statement?
This is very common logic for all routines for which there is even the
remotest possibility that some data has come from an untrusted source.
Eeek! well if you insist (type bound)
someType -EPERM
someType -EFAULT
sometype -EINVAL
someType -EDOSOMETHING
//method
someType checkSomething(data){
someType result = -EINVAL //or your most likely or 'safest' result
if not (you are permitted to do this):
result = -EPERM
if not (you've given me some valid data):
result = -EFAULT
if not (you've given me some sensible data):
result = -EINVAL
else
result = -EDSOMETHING
return result
}
//cohesive, encapsulated, reusable and easy to read
//later
if(checkSomething(data) == EDOSOMETHING){
actually_try_to_do_something_with(data)
}
else{
//who knows
}
What do you think ?
~Andrew
P.S. like the sig.
thanks
--
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.
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