Hi Nick,
Yep, PEP 315. Sorry about that.
Now, about your suggestion
do:
<setup code>
while <condition>
<loop body>
else:
<loop completion code>
This is pythonic, but not logical. The 'do' will execute at least once, so
the else clause is not needed, nor is the <loop completion code>. The <loop
body> should go before the while terminator.
I'm bound to reiterate my proposal:
<before loop code>
do:
<loop body>
<setup code>
while <condition>
<after loop code>
Example (if you know there will be at least one val).
source.open()
do:
val = source.read(1)
process(val)
while val != lastitem
source.close()
The c syntax is:
do
{
block of code
} while (condition is satisfied);
The VB syntax is:
do
block
loop while <cond>
Cheers & thanks for your reply,
Hans Polak.
-----Original Message-----
From: Nick Coghlan [mailto:[EMAIL PROTECTED]
Sent: domingo, 01 de octubre de 2006 6:18
To: Hans Polak
Cc: [email protected]
Subject: Re: [Python-Dev] PEP 351 - do while
Hans Polak wrote:
> Hi,
>
>
>
> Just an opinion, but many uses of the 'while true loop' are instances of
> a 'do loop'. I appreciate the language layout question, so I'll give you
> an alternative:
>
>
>
> do:
>
> <body>
>
> <setup code>
>
> while <condition>
>
I believe you meant to write PEP 315 in the subject line :)
To fully account for loop else clauses, this suggestion would probably need
to
be modified to look something like this:
Basic while loop:
<setup code>
while <condition>:
<loop body>
<setup code>
else:
<loop completion code>
Using break to avoid code duplication:
while True:
<setup code>
if not <condition>:
<loop completion code>
break
<loop body>
Current version of PEP 315:
do:
<setup code>
while <condition>:
<loop body>
else:
<loop completion code>
This suggestion:
do:
<setup code>
while <condition>
<loop body>
else:
<loop completion code>
I personally like that style, and if the compiler can dig through a function
looking for yield statements to identify generators, it should be able to
dig
through a do-loop looking for the termination condition.
As I recall, the main objection to this style was that it could hide the
loop
termination condition, but that isn't actually mentioned in the PEP (and in
the typical do-while case, the loop condition will still be clearly visible
at
the end of the loop body).
Regards,
Nick.
--
Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia
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