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Posted to derby-dev@db.apache.org by Jan Hlavatý <hl...@code.cz> on 2004/09/01 07:39:55 UTC

Bad habits: << 0

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I have noticed there are a lot of << 0 in the code.
While it may make the code a bit more readable,
I remind you it DOES generate unnecesary code in classfiles (two instructions).
I suggest we remove it and refrain from using it in the future.

Jan

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Re: Bad habits: << 0

Posted by Daniel John Debrunner <dj...@debrunners.com>.

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Jan Hlavatý wrote:

| I have noticed there are a lot of << 0 in the code.
| While it may make the code a bit more readable,
| I remind you it DOES generate unnecesary code in classfiles (two
| instructions).
| I suggest we remove it and refrain from using it in the future.
|
| Jan

Cloudscape has always used the jikes compiler for compilation and it
optimises the << 0 away in the generated byte code. Thus as a closed
source project it was an acceptable practice.

Now, I agree that since Derby is open source and javac does not seem to
optimise this away, even with -O, its use should be stopped.

Note that the jar files produced by jikes are significantly smaller than
those produced by javac. I think javac leaves unused string constants in
the .class file, I think references to classes that were used during
compilation, e.g. for bringing in static final constants.

Dan.
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