Re: [pygame] PixelArray question

["Brian Fisher" <brian@xxxxxxxxxxxxxxxxxxx>]

Hey Lenard,
thanks for testing the script I sent. The results confirm that an
earlier statement "p's lifetime will be limited to the with ... :
block anyhow" is not true, meaning with as wouldn't be supported
merely by making the PixelArray object lock and unlock as it is
created and deleted.

Also, I think what you proposed as an implementation of __exit__ below
wouldn't be sufficient (reasons below)

On 8/27/07, Lenard Lindstrom <len-l@xxxxxxxxx> wrote:
> Brian Fisher wrote:
> > On 8/26/07, Marcus von Appen <mva@xxxxxxxxxxxx> wrote:
> __exit__ simply releases the surface lock:
> def __exit__(self, exc_type, exc_val, exc_tb):  # exception stuff is ignored
>     self.unlock()  # Assumes PixelArray has an unlock method.
>     return False  # let any exceptions propagate
>
so if __exit__ just calls unlock, than how would PixelArray know not
to unlock when destructs? thereby unlocking one too many times. Also,
because __enter__ doesn't lock, you wouldn't be able to use "with" on
the same PixelArray twice (a very reasonable way to try and use it, if
you are someone who uses the "with" statement with locks in order to
define critical section stuff)

in particular, I think a proper "with" implementation ought to be able
to support something like this:

p = PixelArray(surface)
with p:
  p.do_stuff()

with p:
  p.do_more_stuff()

... while getting the locking all right