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Re: [IndexedDB] Passing an empty array to IDBDatabase.transaction

From: Cameron McCormack <cam@mcc.id.au>
Date: Tue, 18 Oct 2011 00:14:01 -0400
Message-ID: <4E9CFD09.5040701@mcc.id.au>
To: Jonas Sicking <jonas@sicking.cc>
CC: public-webapps@w3.org
On 17/10/11 7:19 PM, Jonas Sicking wrote:
> I sort of like the short-cut since it seems like a very common case
> for web developers to want to create a transaction which only uses a
> single objectStore.
>
> But I agree it's not a huge win for developers as far as typing goes
> (two characters).
>
> I *think* we can move the validation into the IDL binding these days.
> Something like:
>
> interface IDBDatabase {
>    ...
>    transaction(DOMStringList storeNames, optional unsigned short mode);
>    transaction(DOMString[] storeNames, optional unsigned short mode);
>    transaction(DOMString storeNames, optional unsigned short mode);
>    ...
> }
>
> The WebSocket constructor does something similar.
>
> cc'ing Cameron to confirm that this is valid. It *might* even be the
> case that DOMStringList passes as a DOMString[]?

The above IDL is valid (assuming you stick "void" before the function 
names).  Although DOMStringList is array like enough to work if you are 
not overloading based on that argument (it has a .length and array index 
properties), in this case because the function call is only 
distinguished based on the first argument you will need those separate 
declarations.

You can see what happens when a value is passed as that first parameter 
here:

http://dev.w3.org/2006/webapi/WebIDL/#dfn-overload-resolution-algorithm

If it's a DOMStringList object, since that is an interface type, it will 
definitely select the first overload.  And if you pass an Array object 
or a platform array object, then the second overload will be selected.
Received on Tuesday, 18 October 2011 04:14:46 GMT

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