- Qbs Manual
- Module Item
- Qt Build Suite 1.4.2

LoadableModule Item Probe Item

# Module Item

A `Module` item is a collection of properties and language items that are used for building a product if the product has a dependency on the module. The following (somewhat artificial) module pre-processes text files by removing certain characters from them:

    import qbs
    import qbs.FileInfo
    import qbs.TextFile

    Module {
        property stringList unwantedCharacters: []
        FileTagger {
            patterns: ["*.raw"]
            fileTags: ["raw-txt"]
        }
        Rule {
            inputs: ["raw-txt"]
            Artifact {
                filePath: FileInfo.relativePath(input.filePath, product.sourceDirectory) +
                           "/" + input.fileName + ".processed"
                fileTags: ["processed-txt"]
            }
            prepare: {
                var cmd = new JavaScriptCommand();
                cmd.description = "Processing " + input.fileName;
                cmd.sourceCode = function() {
                    var inFile = new TextFile(input.filePath, TextFile.ReadOnly);
                    var content = inFile.readAll();
                    inFile.close();
                    var unwantedChars = product.moduleProperty("txt_processor",
                                                               "unwantedCharacters");
                    for (var c in unwantedChars)
                        content = content.replace(unwantedChars[c], "");
                    var outFile = new TextFile(output.filePath, TextFile.WriteOnly);
                    outFile.write(content);
                    outFile.close();
                };
                return cmd;
            }
        }
    }

And this is how a product would use the module:

    Product {
        type: "processed-txt"
        Depends { name: "txt_processor" }
        txt_processor.unwantedCharacters: ["\r"]
        files: [
            "file1.raw",
            "file2.raw"
        ]
    }

Of course, normally the pre-processed files would not be the target artifacts of the product, but rather serve as inputs to a different rule that will often come from a different module.

How you make your own modules available to Qbs is explained here.

## Special Property Values

For every property defined in a module, Qbs provides the following special built-in values:

### `base`

This value is useful when making use of inheritance. It stands for the value of the respective property in the item one level up in the inheritance chain. For instance:

    Product { // defined in MyProduct.qbs
        Depends { name: "mymodule" }
        mymodule.someProperty: ["value1"]
    }
    ------ some other file ------
    MyProduct {
        mymodule.someProperty: base.concat(["value2"]) // => ["value1", "value2"]
    }

### `original`

This is the value of the property in the module itself (possibly overridden from a profile or the command line). Use it to set a module property conditionally:

    Module { // This is mymodule
        property string aProperty: "z"
    }
    ----------
    Product {
        Depends { name: "mymodule" }
        Depends { name: "myothermodule" }
        mymodule.aProperty: myothermodule.anotherProperty === "x" ? "y" : original // => "y" if myothermodule.anotherProperty is "x", "z" otherwise

### `outer`

This value is used in nested items, where it refers to the value of the respective property in the surrounding item. It is often encountered in groups:

    Product {
        Depends { name: "mymodule" }
        mymodule.someProperty: ["value1"]
        Group {
            name: "special files"
            files: ["somefile1", "somefile2"]
            mymodule.someProperty: outer.concat(["value"]) // => ["value1", "value2"]
        }
    }

## Module Properties

Property | Type | Default | Description
--- | --- | --- | ---
additionalProductFileTags | string list | empty list | The elements of this list will be added to the `type` property of a product that has a dependency on the module.
condition | bool | `true` | Controls whether the module is enabled. If this property is `false`, the surrounding `Module` item will not be considered in the module look-up.
present | bool | `true` | This property is read-only. Its value is `false` if and only if the respective `Depends` item had its `required` property set to `false` and the module was not found.
setupBuildEnvironment | script | `undefined` | Script for setting up the environment in which the project is built. Use the `putEnv`, `getEnv`, and `unsetEnv` functions to alter the environment. The return value of this script is ignored.
setupRunEnvironment | script | `setupBuildEnvironment` | Script for setting up the environment in which the project is run.
validate | script | `undefined` | Script that is run after the module is loaded. It can be used to check property values and throw errors in unexpected cases. The return value is ignored.

LoadableModule Item Probe Item