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From: Jonathan Ellis <jbellis@gmail.com>
Date: Tue, 27 Oct 2009 14:14:08 -0600
Message-ID: <e06563880910271314j7a139fads3ea9a4d2627e8a21@mail.gmail.com>
Subject: Re: Performance of get
To: cassandra-user@incubator.apache.org
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On Tue, Oct 27, 2009 at 2:00 PM, Christopher McKenzie
<cmckenzie@iizuu.com> wrote:
> Exceptions are a special feature of languages often with their own keywor=
ds, primitives, and usually chapters in books. =A0I don't profess to be an =
expert in the various exception models for all the versions of various impl=
ementations of C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Coc=
oa, Smalltalk, and OCaml that thrift supports. =A0But I would claim that, w=
ith such a large heterogeneous and dynamic support base, one should use som=
ething as varied and unpredictable as the exception handling models with gr=
eat care and I don't "personally feel" that the understandably expected err=
or case of Get should be escalated to be handled by this mechanism.

There are basically two sane options for looking up a key that doesn't
exist.  One is to return null or the equivalent; the other is to raise
an exception.  There are pros and cons for each, and examples of
languages whose stdlib behaves either way.  So a blanket Exceptions
Are Not Idiomatic For Key Lookup statement is misguided.

And as it happens, Thrift does not support returning null values at
all, so from there the natural choice was obvious.

-Jonathan