Re: creating objects

[Marcus G. Daniels]

>>>>> "MA" == Myriam Abramson <address@hidden> writes:

MA> What is the difference between:

MA> EZBinC ezbinCreating = new EZBinCImpl (new EZBinImpl ());
MA> ezbinCreating.createBegin(aZone);
MA> ...
MA> EZBin ezbin = (EZBin) ezbinCreating.createEnd();

MA> and simply 

MA> EZBin ezbin = new EZBinImpl(aZone);

Precisely, the difference is the possibility of the open-ended "...".
In most common cases Swarm has the latter, easier, using-phase
constructor for the `normal' usages of the class, but there are still
a fair number of classes where the explicit phase switch is required.
Any time there are a just few configurations for a class based on a
larger set of possibilities it tends to be easier to require the
phase-switch idiom.  In other cases, the feature may not have these
`convenience' constructors just because the feature doesn't get used a lot.

For the curious, the variant constructors are automatically created
for any declared +create:whatever: factory methods in the Swarm
interface files.  In other words, to get the easy-to-use constructor
on the Java side, it is necessary to implement +create:whatever:
methods on the Objective C side.  For example, src/analysis/analysis.h
& src/analysis/EZGraph.m have several such +create:whatever: methods.


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