Re: [SAGA-RG] Python SAGA language bindings: how to express explicit object destruction?
(Added the SAGA mailing list to this thread.) My two cents are: looks like in languages wirth garbage collection (Java and also Python), we need to have a close() method to achieve a side effect on the remote middleware. If it is the right thing for Java, then it is also the right thing for Python. Thilo On Dec 9, 2009, at 3:53 PM, Mathijs den Burger wrote:
Hi all,
We may have overlooked something in the Python SAGA language bindings: how to express explicit object destruction.
The root problem is that many backends have to be stopped explicitly. An example is the XtreemOS job submission system, but many others exist as well.
For cleanup, SAGA defines destructors. However, this does not work in languages that do not support explicit object destruction (e.g. Java). The Java language bindings therefore added the method session.close(), which explicitly closes all running middleware that uses that session.
Python contains a 'del' statement. However, that is not the same as a 'delete' in C++. The 'del' in Python only decreases a refcount. Relying on Python's destructors (e.g. the __del__ methods in an object) can therefore be tricky [1], and makes it not very well suited to shutdown middleware.
So: should we add a session.close() method to the Python language bindings as well?
best, -Mathijs
[1] http://www.electricmonk.nl/log/2008/07/07/python-destructor-and-garbage-coll...
-- Thilo Kielmann http://www.cs.vu.nl/~kielmann/
+1 for close() Also, we have close on other objects which need explicit resource freeing before destruction (see 2.5.4 and 2.5.5 of GFD.90). Best, Andre. Quoting [Thilo Kielmann] (Dec 09 2009):
Cc: Manuel Franceschini <livewire@koltern.com>, Andre Merzky <andre@merzky.net>, Hartmut Kaiser <hkaiser@cct.lsu.edu>, SAGA RG <saga-rg@ogf.org> From: Thilo Kielmann <kielmann@cs.vu.nl> To: Mathijs den Burger <mathijs@cs.vu.nl> Subject: Re: Python SAGA language bindings: how to express explicit object destruction? Date: Wed, 9 Dec 2009 16:43:38 +0100
(Added the SAGA mailing list to this thread.)
My two cents are:
looks like in languages wirth garbage collection (Java and also Python), we need to have a close() method to achieve a side effect on the remote middleware.
If it is the right thing for Java, then it is also the right thing for Python.
Thilo
On Dec 9, 2009, at 3:53 PM, Mathijs den Burger wrote:
Hi all,
We may have overlooked something in the Python SAGA language bindings: how to express explicit object destruction.
The root problem is that many backends have to be stopped explicitly. An example is the XtreemOS job submission system, but many others exist as well.
For cleanup, SAGA defines destructors. However, this does not work in languages that do not support explicit object destruction (e.g. Java). The Java language bindings therefore added the method session.close(), which explicitly closes all running middleware that uses that session.
Python contains a 'del' statement. However, that is not the same as a 'delete' in C++. The 'del' in Python only decreases a refcount. Relying on Python's destructors (e.g. the __del__ methods in an object) can therefore be tricky [1], and makes it not very well suited to shutdown middleware.
So: should we add a session.close() method to the Python language bindings as well?
best, -Mathijs
[1] http://www.electricmonk.nl/log/2008/07/07/python-destructor-and-garbage-coll... -- Nothing is ever easy.
participants (2)
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Andre Merzky -
Thilo Kielmann