[PD] sending image from of / libpd

[Peter Brinkmann]

On Wed, Aug 31, 2011 at 9:01 AM, Dan Wilcox <danomatika at gmail.com> wrote:

>
> On Aug 31, 2011, at 8:45 AM, Peter Brinkmann wrote:
>
>
> On Wed, Aug 31, 2011 at 6:25 AM, Dan Wilcox <danomatika at gmail.com> wrote:
>
>> I think it's much simpler to just add a call to get/set the message limit,
>> say:
>>
>> int libpd_max_message_length();
>> void libpd_set_max_message_length(int length);
>>
>> This doesn't break any current code.
>>
>> Having to set a custom limit each time is far more tedious then just
>> setting it at startup.
>>
>
> Actually, breakage of current code is a feature as far as I am concerned
> because it makes people aware of the change, and it should be harmless
> because it's easy to fix.  The language bindings for Java and Objective-C
> actually became simpler when I updated them for the new version.
>
> I don't think the new signature of libpd_start_message is tedious, really.
> Essentially, I see two use cases: Either you know an a-priori limit on your
> message length, in which case there's the tiny extra effort of passing in
> the limit every time you start a message, or you don't have an a-priori
> limit, in which case you need to check the length before assembling a
> message anyway.
>
> Another aspect is API design.  One feature of a good API is that it's
> difficult to use incorrectly.  With a separate call for setting the message
> limit, people will forget that the limit is a consideration.  With the
> current solution, people will briefly contemplate the length of each message
> they start, which is a good thing.
>
>
> ... but you can simply return an error or print a message complaining when
> the message is too long. My whole point is that most people won't bother
> changing the limit and those that do will just pick a larger size with
> plenty of space anyway. It's too much work to bother setting it EACH and
> EVERY time. It's far LESS elegant, and dare I say intuitive. It seems like
> an unnecessary step. [eople that have problems will only run into this once,
> increase the max size, and then be fine. Why force them to compute a size
> manually each time when they could just be happily adding objects ... ?
>

Actually, I don't mean to make people compute the size every time  The
length parameter in libpd_start_message merely makes sure that you'll have
enough space for that many elements; the number of elements in the actual
message may be smaller.  If you know that your messages will never exceed a
certain length, then you can simply use that maximum length every time.  In
that situation, I would just wrap the call to libpd_start_message in a macro
or a convenience function to get exactly the effect that you want.



> In case, my wrapper will include max message size get/set functions and
> complain to cout when something is out of bounds.
>

And with the streaming API that you've built in C++, that's the right thing
to do:)
Cheers,
      Peter
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