Tentacle behaviour can be defined through text configuration files rather than being hard coded as in previous releases. The file format tries to fix some of the weaknesses in SciTE's properties files. The current implementation does not yet provide some of SciTE's properties files features such as variable substitution and conditional logic. Variable substitution will definitely go in but conditionals may not or may be implemented in a much different way.
Tentacle divides settings into options files and mode files. Mode files define the behaviour for particular languages. Options files are for setting global parameters, user preferences, and user overrides of mode file settings.
Options files define a set of properties with values. Only one options file, user.options, in the user's home directory is currently used but in the future there will be global, user, and local options files similar to SciTE.
| user.options |
| # Preferences for this user |
| caret.color=#FF0000 |
| selection.style:back=#FFFFC7,fore=#400000 |
| style: |
| Comment:fore=#008000,font=Comic Sans MS |
Lines that start with '#' like the first line are comments.
The next line defines the color of the caret to be red. Property names are made up of parts separated by the '.' character. These multi-part names define a hierarchy much like a file system. All of the settings associated with the caret would start with "caret." allowing the caret settings to be manipulated as a group. caret.color is itself a simple item with a single value.
selection.style is then defined as a compound value with both back and fore colors. The ':' operator is used rather than '=' to indicate a compound assignment as otherwise '=' and ',' could not be used inside values in assignments. This compound assignment is exactly equivalent to
| ··· |
| selection.style.back=#FFFFC7 |
| selection.style.fore=#400000 |
| ··· |
The 'style:' line starts an indented segment where all property names start with 'style.'. This avoids repeating the same prefix many times and groups related properties. The segment ends with the first line that is less indented than the first line. It should also end before a line that has equivalent indentation to the 'style:' line but that is not yet working. Case is used for matching in property names but has no other significance so the 'Comment' name starts with an upper case 'C' because that is what the system calls that style. These two lines are equivalent to:
| ··· |
| style.Comment.fore=#008000 |
| style.Comment.font=Comic Sans MS |
| ··· |
In SciTE, only some settings (style and command options) allowed compound assignments but Tentacle allows this for all settings. If a value needs to contain '=' or ',' characters then it can be set with a simple assignment or by using the quoting character '\'.
| ··· |
| Word:bold=1,backdecoration={type=RoundedBox,fore=#0080A0,alpha=40,alphaoutline=80} |
| ··· |
Compound values can be set inline using '{' and '}'.
Mode files define behaviour for a language or group of languages. They create a name scope based on their file name so will not interfere with other mode files or options files. Mode files use file names like "<xxx>.mode" and the names of all properties defined within the mode file will start with "mode.<xxx>" so the file
| python.mode |
| selection.style:fore=#000080 |
will define a property "mode.python.selection.style.fore".
All property evaluations act relative to a current mode. If a Python file is opened then the current mode could be "mode.python", in which case evaluating "selection.style.fore" would return "#000080". Modes have superclasses from which they inherit properties.
| javascript.mode |
| # Base mode for JavaScript, ECMAScript, ActionScript, etc. |
| # Names are implicitly scoped starting with mode.javascript |
| name=JavaScript |
| extensions=js |
| lexer=CPP |
| keywords.1=abstract assert boolean break byte case catch \ |
| char class const continue default do double else |
| style: |
| Default:fore=#D0D0D0 |
| Comment:fore=#008000,font=Comic Sans MS |
| htmlscripted.mode |
| # Modes for HTML with embedded scripts |
| name=Scripted HTML |
| extensions=html |
| super=mode.html |
| submodes=mode.htmlscripted.js_client |
| layers=mode.base.url |
| # Client side JavaScript mode.htmlscripted.js_client |
| js_client: |
| super=mode.javascript |
| extensions= |
| style: |
| Default:back=#f0f0ff,eolfilled=1 |
In this example, the client side JavaScript mode (mode.htmlscripted.js_client) is a subclass of JavaScript and so inherits the lexer and style properties from mode.javascript. This is specified by the 'super' property and not by inclusion in javascript.mode or by having a common prefix although these could be considered as alternative inheritance techniques. The superclass mode is explicit as that allows for more flexibility across files. Long values can be continued onto the following line by ending the line with a '\'.
HTML allows scripts in multiple languages to be embedded within pages and these are incorporated into the mode by specifying them in the submodes property. In this example, a JavaScript mode is included. This mode is separate from the base JavaScript mode so that it can inherit most settings but choose different settings such as a distinctive background color and extensions is set to "" so that only mode.javascript is trying to claim .js files.
Layers are similar to submodes but are used when a mode is not merged so closely into the main mode but is considered more of an orthogonal feature. Example layers are URL highlighters or spell checkers. The set of layers is defined in the layers property, in this case an URL checker. Layers can use styling information from the main mode, be turned on or off independently of the main mode without disrupting existing state, and be performed as a background task that lags the main mode where the layer is performing a slow task such as parsing a programming language or checking URLs for validity.
SciTE users often incorrectly expect that setting a value in python.properties will only affect Python files. Tentacle avoids this problem by isolating mode files.
Mode files are unable to set top level properties so are only able to affect their own modes and modes that explicitly use them. Options files, however, can define top level properties and can also access mode settings by fully qualifying a setting such as "mode.javascript.name=Basic JavaScript" thus overriding the mode file's choice. Overriding does not work yet.
In SciTE the application decides whether settings are global or local to a lexer or a file pattern so the user is unable to, for example, choose to display XML files as UTF-8 but C++ files as Latin-1. With Tentacle options the user may set any property globally or only within a mode.
With SciTE properties files it is difficult to collect settings from multiple files to create a shared list such as the "Language" menu or mapping extensions to modes. With Tentacle modes files, each mode provides a setting and these are collected by iterating over the full set looking for a particular suffix. When a file is opened the set of extensions properties is checked and the mode that includes the file's extension is used to interpret the file.
This format is somewhat similar to YAML. The reasons for not choosing to use YAML or a subset of YAML are that YAML requires more syntax.
XML can also be used for configuration files but it is a dreadful format to edit manually.
Options and Mode files are encoded in UTF-8.
SinkWorld provides the OptionSet class for holding the users preferences in memory and this includes reading a buffer into an OptionSet but does not include any of the file operations which should be provided by the application. This allows the application to determine its policy on which files to read and what their precedence is. The application may also choose to read preferences from a system registry or database.
Many parts of SinkWorld such as lexers may need configuring and the set of parameters is open ended so it is easier to allow access to the option set object and current mode from lexers.