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Re: [pcgen_developers] Re: [PCGD] Code Meeting April 2009 - Log

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  • Eric Jarman
    Here s a BSD licensed expression parser: http://sourceforge.net/projects/expression-tree/
    Message 1 of 15 , May 3, 2009
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      Here's a BSD licensed expression parser:  http://sourceforge.net/projects/expression-tree/


      On Sun, May 3, 2009 at 11:36 AM, Tom Parker <thpr@...> wrote:


      My biggest concern with JEP is that we are operating under a license exception.  We would need to be *very* clear on how licensing would work in a fork - His project is GPL2, which causes problems for us.  We are using Apache libraries that are not compatible with GPL2. 

      I would strongly vote against any fork which was still operating under an exception - there is *way* to much risk involved since it starts to impact our ability to use code we would have to develop/modify.  The fork would have to be LGPL or Apache licensed (he would have to explicitly license it that way in a public forum, not just in an email to us) or it's a non-starter IMHO.

      I also happen to agree with Andrew - what we're looking for is much simpler than JEP.  The effort spent taking out the complexity we don't want is better spent building up what we DO want.  Parsers really aren't hard.  In fact, we may need to take complexity OUT of the (much simpler) parser I wrote (though we need to add handling of some additional characters inside quotes)

      I also think a fork is actually worse, unless we get extensive test code along with his code.  If we have to spend years developing a test library, then it's better & faster to start from scratch so we can know what we are dealing with and only have to test the subset of what we want & develop (not what people could use if they knew JEP inside and out)

      TP.
      --
      Tom Parker
      thpr@... and tppublic@...

      --- On Sun, 5/3/09, Martijn Verburg <martijnverburg@...> wrote:
      From: Martijn Verburg <martijnverburg@...>
      Subject: [pcgen_developers] Re: [PCGD] Code Meeting April 2009 - Log
      To: pcgen_developers@yahoogroups.com
      Date: Sunday, May 3, 2009, 4:49 AM


      Hi All,

      Searched for alternatives to JEP and also looked for Forks of that library, and
      what do you know! I found a discussion between myself and their main developer
      about forking the project.

      It is a valid option if we want to do that as well.

      Thoughts?

      K

      > Thanks, I'll have a look.
      >
      > andrew
      >
      > 2009/5/2 Tom Parker <thpr@...>:
      > > --- In pcgen_developers@yahoogroups.com, Tom Parker <thpr@>
      wrote:
      > >> I'll dig it up and upload it into a sandbox.
      > >
      > > This is now loaded into sandbox/FormulaCompiler
      > >
      > > Yes, it's a bit of a heavy user of System.err at the moment,
      it's still a bit broken, and the tests aren't *really* tests in the
      jUnit sense, but this really wasn't originally intended for public
      consumption...
      > >
      > > TP.
      > >
      > >
      > >
      > >
      > > ------------------------------------
      > >
      > > Yahoo! Groups Links
      > >
      > >
      > >
      > >
      >
      > <div><br></div>
      >




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    • Tom Parker
      ... Eric, Interesting find, thanks. I think there may be some things we can learn from this even if we can t use it (such as writing expressions back out to
      Message 2 of 15 , May 3, 2009
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        --- In pcgen_developers@yahoogroups.com, Eric Jarman <ejarman@...> wrote:
        >
        > Here's a BSD licensed expression parser:
        > http://sourceforge.net/projects/expression-tree/
        >

        Eric,

        Interesting find, thanks. I think there may be some things we can learn from this even if we can't use it (such as writing expressions back out to Strings).

        My biggest concern with this design is that it is one big method (lots of ifs, etc.) that does the work.

        This is fragile (consider how many times specific operators like '+' appear in the method and how hard it thus is to change). It also seems variable names with numbers are not supported (potentially a problem for us, and also subject to the 'fragile method' problem).

        I think the test cases are useful for us to use as a demonstration, but would be reluctant to recommend this vs. the use of a parser generated by JJTree/JavaCC.

        I think Andrew should take a look at this too, however, as I think he'll be leading up the formula work.

        TP.
      • Andrew Wilson
        ... I glanced at it but it hasn t had any work done for several years. I d assumed it has similar problems to JEP so I didn t pursue it. I ll have another
        Message 3 of 15 , May 4, 2009
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          2009/5/3 Tom Parker <thpr@...>:
          > I think Andrew should take a look at this too, however, as I think
          > he'll be leading up the formula work.

          I glanced at it but it hasn't had any work done for several years.
          I'd assumed it has similar problems to JEP so I didn't pursue
          it. I'll have another look.

          andrew
        • Tom Parker
          I share the time lag concern, but at least useful to look at the archictectural decisions since one of our options is starting fro scratch TP. -- Tom Parker
          Message 4 of 15 , May 4, 2009
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            I share the time lag concern, but at least useful to look at the archictectural decisions since one of our options is "starting fro scratch"

            TP.
            --
            Tom Parker
            thpr@... and tppublic@...

            --- On Mon, 5/4/09, Andrew Wilson <affable@...> wrote:
            From: Andrew Wilson <affable@...>
            Subject: Re: [pcgen_developers] Re: [PCGD] Code Meeting April 2009 - Log
            To: pcgen_developers@yahoogroups.com
            Date: Monday, May 4, 2009, 6:31 AM

            2009/5/3 Tom Parker <thpr@...>:
            > I think Andrew should take a look at this too, however, as I think
            > he'll be leading up the formula work.

            I glanced at it but it hasn't had any work done for several years.
            I'd assumed it has similar problems to JEP so I didn't pursue
            it. I'll have another look.

            andrew


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