Going Dotty With Lazarus/FPC

11 Sep 2012 in Delphi, Lazarus | 29 comments

I am in the middle of writing a much longer post about variations and recent additions to Pascal syntax in Delphi, Oxygene and Lazarus, but at the same time I also decided to start on the process of migrating some of my code to Lazarus and FPC. In the process I have hit upon a snag.

Ever since I discovered that Delphi 7 (SEVEN!) supported “dotted unit names”, I have adopted this style of unit naming in my own code organisation. In Delphi 7 this incurred some less than desirable behaviours in the IDE, since the support for dotted unit names was at that time a little… preliminary.

Sadly, this means that – as far as I can tell – none of my existing units can be used “as-is” in Lazarus and FPC. There is no support for dotted unit names there, not even with FPC set to “Delphi” syntax parsing.

At first I thought this meant that my Lazarus/FPC ambitions were stalled at a disappointingly early stage.

However, not to be deterred I quickly I found that several suggestions have already been made as to how FPC might go about implementing dotted unit names, some of which aim to improve on the approach in Delphi (though in Delphi mode I would expect things to behave in as Delphi-like a way as possible, obviously).

Then I found that some support in this area has already made it’s way into the latest development version of the FPC compiler.

All I need to do now is figure out how to get Lazarus working with this later, pre-release build of the FPC compiler (something which I gather is possible, just not “plug-and-play”). I also need to be a little cautious as, being pre-release, whatever form the dotted unit name support in the current FPC trunk takes, it could still change.

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29 comments

  1. Andreas’s avatar

    Andreas on 11 Sep 2012 at 23:20

    Hm. I don’t think using dots in Unit-Names makes much sense.
    All it does is to create additional ambiguities for the parser and to the reader
    of your code whenever you prefix a type with a Unit-Name.
    Why don’t you just use CamelCase or underscores?

    1. Sebastian’s avatar

      Sebastian on 13 Sep 2012 at 00:59

      If you only use CamelCase for long unit names one can’t quickly see which part of the unit name is only a prefix and which is relevant in my current namespace. They are used in Delphi, Java, C#, … and in my opinion this has many advantages.

      Underscores? Do you mean this serious? For external API identifiers this is ok, but for identifiers in own code? omg… in my opinion code with underscores looks really dirty.

  2. Stefan Glienke’s avatar

    Stefan Glienke on 11 Sep 2012 at 23:24

    FPC supports dotted unit names. But Lazarus (or the used FPC version?) does not.

    1. Deltics’s avatar

      Deltics on 12 Sep 2012 at 08:06

      Yep, as I understand it Lazarus 1.0 supports them in the IDE (in the sense that it no longer rejects them in various places as “invalid identifiers”) but the FPC version that is in the release distro (FPC 2.6.0) does not. Dotted unit names is in FPC 2.7.x and is subject to change.

  3. Stefan Glienke’s avatar

    Stefan Glienke on 11 Sep 2012 at 23:32

    There are daily snapshots of Lazarus with FPC 2.7.1 just google for it. Last time I checked (few months ago) it was pretty much broken but the dotted unit names worked.

  4. Mark Daems’s avatar

    Mark Daems on 11 Sep 2012 at 23:56

    Getting Lazarus to work (on Windows at least) is as simple as:
    - Getting a copy of the fpc source somewhere using svn
    - Compiling this code (starting with the old compiler version should work)
    - Pointing to the new compiler and source in the lazarus compiler options
    - Rebuild Lazarus

    1. Deltics’s avatar

      Deltics on 12 Sep 2012 at 08:08

      Yes, simple, but not plug-and-play and quite a few manual steps in the process (the instructions I found included creating a BAT file necessary to compile the compiler). At the time that I came across this I had plenty of other, more important things to do. By the time I’ve done those the feature might be stabilised and part of a more straightforward install (the stabilised part is the most important to me).

      1. Marco van de Voort’s avatar

        Marco van de Voort on 15 Sep 2012 at 01:29

        I don’t recommend running Lazarus with 2.7.1 for production anyway. (and it will probably remain that way quite a while).

        This because 2.7.1 changes things in unicode support (D2009+ like) that Lazarus hasn’t adapted too.

        That being said, IMHO dotted units isn’t exactly the nicest feature. One I would gladly do without (yes I know XE2 makes it near mandatory, which is why I’m on XE)

  5. Mark Daems’s avatar

    Mark Daems on 11 Sep 2012 at 23:57

    Oops : Getting Lazarus to work with fpc trunk, I meant.

  6. Denis’s avatar

    Denis on 12 Sep 2012 at 00:10

    I’m not completely sure, but I guess & symbol isn’t included in FPC 2.6.0 release also.

    Like:

    var
    &Type: integer; // though it works in 2.7.1

    You can check it also.

    1. Deltics’s avatar

      Deltics on 12 Sep 2012 at 08:11

      Maybe, maybe not. But this feature in Delphi is one of those that breaks the IDE (up to and including XE2 at least) so I never use it (try using Class Completion when your class includes a property that uses the ‘&’ prefix).

      1. Denis’s avatar

        Denis on 13 Sep 2012 at 03:25

        I agree. I try to avoid such expressions too.

  7. Snorkel’s avatar

    Snorkel on 12 Sep 2012 at 00:34

    Did you try the 1.1 nightly builds with fpc
    2.6.1?

  8. Kryvich’s avatar

    Kryvich on 12 Sep 2012 at 04:37

    Actually, they support the dotted names of units in FPC 2.7.1. But you’ve to download and build it yourself from sources:
    http://www.freepascal.org/develop.var
    I’ve found out that FPC 2.7.1 has some bug fixes too.

    1. Kryvich’s avatar

      Kryvich on 12 Sep 2012 at 04:44

      Sorry, I’ve written the answer without having read up your message.

  9. Felipe’s avatar

    Felipe on 12 Sep 2012 at 05:18

    This new release also supports the Java Virtual Machine and Dalvik targets, so the RemObjects Oxygene now has a free competitor.

    1. Ivan Levashew’s avatar

      Ivan Levashew on 12 Sep 2012 at 20:38

      GNAT also has JVM and .NET targets. One more free competitor: https://libre.adacore.com/

  10. Peter’s avatar

    Peter on 12 Sep 2012 at 12:30

    You always get the latest snapshot of FPC/Lazarus here:

    ftp://newwiki.freepascal.org/pub/lazarus/snapshots/

    I can recommend: Lazarus-1.1-38611-fpc-2.7.1-20120911-win32.exe

    1. Deltics’s avatar

      Deltics on 12 Sep 2012 at 12:42

      Excellent, thanks for that! :)

  11. avra’s avatar

    avra on 12 Sep 2012 at 21:21

    You might want to take a look at FPCUP – automated command line tool that downloads current FPC & Lazarus from SVN, compiles and installs it – separate from existing installs (snapshots, release builds, other SVNs). Default settings need to be modified to download latest FPC 2.7.1.

    http://www.lazarus.freepascal.org/index.php?topic=15919.0

  12. Sven’s avatar

    Sven on 13 Sep 2012 at 19:22

    You have to keep in mind that FPC 2.6.0 was released at the beginning of 2012. Even more it was branched last year in July/August, so many of the more intrusive features (regarding compiler code) were not merged to that branch (some smaller ones were included in 2.6.1 and thus will be part of 2.6.2). Features that are only supported in 2.7.1 for example are – as you noticed – dotted unit names and the code page aware string.

    Just in case: if you heavily use generics in your Delphi code you should use 2.7.1 as 2.6.0 is not nearly as compatible as 2.7.1 is (though things like constraints and generic methods are still missing and inline specialization is not yet working as flawless as possible – I’m working on them ;) ).

    Regards,
    Sven

  13. Hans Joerg’s avatar

    Hans Joerg on 15 Sep 2012 at 06:35

    Have a look at codeTyphon. Has Lazarus+FreePascal+Tools+Free Components packages+Free Libraries and is normaly build from the latest fpc / lazarus trunk.

    Hope it helps

    cu Ha-Joe

    1. Boz’s avatar

      Boz on 17 Sep 2012 at 13:42

      I think Codetyphoon is still using Lazarus 0.92 :-(

      ..probably due for an update soon :-)

      1. avra’s avatar

        avra on 17 Sep 2012 at 20:31

        Current CodeTyphon is using this:
        Lazarus 1.1.0 Source from SVN 28-7-2012 Rev 38083
        FreePascal 2.7.1 Source from SVN 22-7-2012 Rev 21951

        Lazarus 0.9.2.9 was last used back in 2010.

        http://www.pilotlogic.com/codetyphon/changeslog.txt

      3. Boz’s avatar

        Boz on 19 Sep 2012 at 08:46

        I’ll correct myself, it seems CodeTyphoon rebuilds the latest CSV, just tried it and got Lazarus 1.1

        This is getting better and better :-)

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