[Twisted-Python] dynamic FTP realm

[Paul Wiseman]

On 29 September 2012 21:21, <exarkun at twistedmatrix.com> wrote:

> On 07:44 pm, poalman at gmail.com wrote:
> >
> >Thank you. I've made quite a bit of progress and now have my own
> >Portal,
> >CredentialsChecker, Realm, Shell, and FilePath object.
> >
> >One thing I haven't been able to work out is, when I override, lets say
> >listdir for example in FilePath, I need to make a webcall to find out
> >the
> >folder contents, how can I make this call asynchronously?
> >
> >I'm guessing I need to used deferred in someway, but seeing as listdir
> >doesn't return deferred objects I'm not sure how to make it work.
> >
> >As listdir gets called from the Shell I guess I could change how
> >blocking
> >calls in my FilePath object get called?
>
> The place to customize listing the contents of a directory is in the
> shell.  More specifically, in an implementation of IFTPShell.list.  It's
> almost certainly the case that you should *not* have a FilePath subclass
> with overridden methods.  Instead, you should have a `list`
> implementation on your shell that returns the desired results.  And
> since `IFTPShell.list` is allowed to return a Deferred, you no longer
> have a problem performing asynchronous operations.
>
> Jean-Paul
>
>
 That is likely a much better idea! Will I need to use some threading if
I'm making web calls then from list? Presumably if I don't the whole
process will block while it's waiting for web responses?

I've seen there is a deferToThread but I'm not too sure how to use it, do I
just need to return it?
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