All posts by Dominik

Dominik is a PhD student at the Control Theory and Robotics Lab, TU Darmstadt, as part of the Research Training Group GKMM (GRK1362). My research focuses on state estimation in distributed systems. As hobby, I contribute to the KDE project and work on the Kate application and editor component.

Using the Projects Plugin in Kate

Introducing the Projects Plugin for KDE SC 4.10

The basic idea of the Projects plugin is to have a structured list of files belonging to the  project with the following properties:

  1. provide a structured view of the files
  2. make it easy and very fast to open and switch projects
  3. support search & replace for a project
  4. provide simple auto completion
  5. make it simple to quickly open files in the project
  6. support for building the project

We’re going to address all these points now.

1. Provide a Structured View of the Files

Once the “Projects Plugin” is loaded in the Kate config page, a sidebar appears that lists all projects as well as the projects files as follows:

As you can see, the currently active project is “Kate”, and it’s contents is listed in the tree view. Clicking on files in the tree view opens the file in the editor. Further, a context menu is provided with which you can open files with other applications, such as a .ui file with Qt Designer.

2. Switching Projects

The idea is that you never have to open a project manually, this is even not supported at all. Hence, what happens if you open a file, the Project Plugin quickly scans the folder and its parent folders for a .kateproject file. If found, the project is automatically loaded. Very simple and efficient.

Further, if you open another document in Kate, that belongs to another project, the Project plugin automatically switches the current project. So intuitively, always the correct project is active. Of course, you can also switch the currently active project through the combo box.

3. Search & Replace in Projects

Kate has a “Search & Replace” plugin that shows up in the bottom sidebar. If a project is loaded and you open the “Search & Replace” sidebar, it automatically switches to the mode to search & replace in the current project, which usually is exactly what you want:

4. Simple Auto Completion

With the knowledge of all files belonging to a project, the Project plugin provides simple auto completion facilities based on ctags. If a project is initially opened, ctags parses all project files in a background thread and saves the ctags information to /tmp. This file then is used to populate the auto completion popup in Kate. In contrast, without this auto completion, Kate was only capable of showing auto completion items based on the words in the current file. So the auto completion provided by the Project plugin is much more powerful.

If ctags is missing, a passive popup warns you about this. It is also noteworthy, that the ctags file in /tmp is cleaned up when Kate exists, so you the plugin does not pollute any folder with unwanted files.

5. Quick Opening Files

As clicking on files in the tree view is not the fastest way to open a file, Kate provides a built-in quick open mechanism you can activate with CTRL+ALT+o. What you the get is a list like this:

You can filter by typing parts of the file name you are looking for, and you can also navigate with the arrow keys and page up/down through the list. Hitting enter activates the selected file, while escape hides the quick open view again.

Further, the quick open remembers the previous file. So when you change to the quick open view the previously activated  file is automatically selected and you just need to hit enter, which comes very handy at times.

6. Support for Building the Project

Another feature is to have support in the Build plugin, so that it automatically is configured correctly.

Creating Projects

Currently, creating a project requires some manual work, although it is really not much. You just have to create a .kateproject file in the root folder of the project. For instance, the Kate .kateproject file looks like this:

{
  "name": "Kate"
, "files": [ { "git": 1 } ]
}

As you may have noted, this is JSON syntax (because there is a nice jason library for Qt to parse this). The project name is “Kate”, and the files contained in should be read from git.

What’s also supported instead of “git” is subversion through “svn” and mercurial through “hg” (btw, it would be nice to have support for other version control systems as well *hint*). If you do not want to read from a version control system, you can tell it to recursively load files from directories as follows:

{
  "name": "Kate"
, "files": [ { "directory": "kate", "filters": ["*.cpp", "*.h", "*.ui", "CMakeLists.txt", "Find*.cmake"], "recursive": 1 } ]
}

Here, subfolders and filters define what’s part of the project. You can also mix version control and files based on filters.

If you want to add support for the Build plugin, you could write a .kateconfig like this:

{
  "name": "Kate"
, "files": [ { "git": 1 } ]
, "build": {
    "directory": "build"
  , "build": "make all"
  , "clean": "make clean"
  , "install": "make install"
  }
}

Hopefully, these examples help you to setup your own project.

Kudos

Kudos go to Christoph, he implemented all the features in here. The Project plugin will be shipped with  KDE SC 4.10, and you should really try it out :-)

Contribute to Kate

Currently we are at the Kate/KDevelop sprint in Vienna. Christoph and me took the time to look a bit around in the net for Kate, and more or less accidently stumbled over quite a lot of extensions by our users. Here are some examples:

Kate has just about 20 plugins written in C++. And, ironically, there are more plugins for Kate written in python. This is totally awesome, but still, the Kate developers didn’t even know about it ?¿? :-o

So we started contacting these potential contributors, and also asked why they e.g. upload it in some other git repository. One time, we got the answer, that they uploaded it somewhere to share it with other users. But really, the perfect way to share additions for Kate is to put it into the Kate git repository directly. This is how open source works…

So if you make additions or changes to Kate, please let us know, create a patch and send it to review board, come to our developer sprints, come to the annual KDE conferences… Talk to us, usually we are all pretty friendly and really happy about every single contribution!

Remove Trailing Spaces

Up to KDE 4.9, Kate Part had support to remove trailing spaces in two ways:

  1. Remove trailing spaces while editing
  2. Remove trailing spaces on save

The reasoning behind removing trailing spaces while editing is that when working on a document, we want to keep our own changes clean of trailing spaces. This way, we can for instance provide patches that are not cluttered with whitespace changes, and we just change lines that we really want to change.

The implementation of this feature unfortunately had quite some regressions that we were able to “fix” over time. For instance, you do not want to remove trailing spaces if the cursor is currently in the trailing spaces area. This alone means we have to kind of remember that we touched this line, and then remove it later. This was always hacky, and in fact, there are still corner cases that did not work.

For KDE 4.10, the both options were merged into just one option Remove trailing spaces with three possible values:

So we only support removing trailing spaces on save from KDE 4.10 on. The implementation is now very clean and based on the line modification system available since KDE 4.8: Thanks to this system we know exactly which lines in the document were changed. So if you choose “Modified Lines” in the configuration, trailing spaces of these modified lines are removed, and other lines remain untouched. If you choose “Entire Document”, then all trailing spaces in the document will be removed. And, needless to say, “Never” implies that trailing spaces are never removed.

For compatibility, the old mode-lines “remove-trailing-space” and “replace-trailing-spaces-save” are still supported, but you’ll get a kWarning() on the console. All these changes are also documented in the Kate handbook (once KDE 4.10 is released). From KDE 4.10 on, you should switch to the modelines

- remove-trailing-spaces none;
- remove-trailing-spaces modified;
- remove-trailing-spaces all;

Hope you like it…