Re: Mixing OO and DB
From: Robert Martin <unclebob_at_objectmentor.com>
Date: Thu, 6 Mar 2008 01:21:44 -0600
Message-ID: <2008030601214447408-unclebob_at_objectmentorcom>
>
> [snip]
>
> simpler? Ah, no.
Date: Thu, 6 Mar 2008 01:21:44 -0600
Message-ID: <2008030601214447408-unclebob_at_objectmentorcom>
On 2008-03-04 18:01:51 -0600, Gene Wirchenko <genew_at_ocis.net> said:
> Robert Martin <unclebob_at_objectmentor.com> wrote:
>
>> On 2008-03-04 00:25:43 -0600, topmind <topmind_at_technologist.com> said:
>
> [snip]
>
>>> Um, like what if there are zero Bob's or 200 Bob's in the actual
>>> system? Are you gonna arbitrarily pick one?
>>
>> Don't be silly. find("Bob") will either return the object for "Bob" or
>> it will return nothing. You would only use this method if you knew
>> that there could be no more than one "Bob".
>
> So if there is more than one "Bob", the method will return
> nothing?
If there is more than one bob, the function will throw an exception.
>> If there could be more than one "Bob", then you would use a function
>> like: find_all("Bob") which would return a list of all the matching
>> objects.
>
> The supposedly more complicated SQL uses the same query for each.
> Then, you check how many rows were returned. Writing two methods is
> simpler? Ah, no.
Pretending that 1 is plural is simpler? Sometimes you want to *assert* that there is just one.
-- Robert C. Martin (Uncle Bob) | email: unclebob_at_objectmentor.com Object Mentor Inc. | blog: www.butunclebob.com The Agile Transition Experts | web: www.objectmentor.com 800-338-6716 |Received on Thu Mar 06 2008 - 08:21:44 CET