Giter8 is a command line tool to generate files and directories from templates published on github or any other git repository. It's implemented in Scala and runs through the sbt launcher, but it can produce output for any purpose.

You can install giter8 and other Scala command line tools with Conscript. This will setup Conscript in ~/bin/cs:

curl https://raw.githubusercontent.com/foundweekends/conscript/master/setup.sh | sh

(See Conscript's readme for a non-unixy option.) Once cs is on your path, you can install (or upgrade) giter8 with this command:

cs foundweekends/giter8

To make sure everything is working, try running g8 with no parameters. This should download giter8 and its dependencies, then print a usage message.

When it's time to upgrade to a new version of giter8, just run the same cs command again.

Giter8 is also installable with the OS X package manager Homebrew:

$ brew update && brew install giter8

Template repositories must reside on github and be named with the suffix .g8. We're keeping a list of templates on the wiki.

To apply a template, for example, softprops/unfiltered.g8:

$ g8 softprops/unfiltered.g8

The .g8 suffix is assumed:

$ g8 softprops/unfiltered

Either way, giter8 resolves this to the softprops/unfiltered.g8 repository and queries github for the project's template parameters. Alternatively, you can also use a git repository full name>

$ g8 https://github.com/softprops/unfiltered.g8.git

You'll be prompted for each parameter, with its default value in square brackets:

name [My Web Project]: 

Enter your own value or press enter to accept the default. After all values have been supplied, giter8 fetches the templates, applies the parameters, and writes them to your filesystem.

If the template has a name parameter, it will be used to create base directory in the current directory (typical for a new project). Otherwise, giter8 will output its files and directories into the current directory, skipping over any files that already exist.

Once you become familiar with a template's parameters, you can enter them on the command line and skip the interaction:

$ g8 softprops/unfiltered.g8 --name=my-new-website

Any unsupplied parameters are assigned their default values.

Giter8 will use your ssh key to access private repositories, just like git does.

The g8 runtime looks for templates in the src/main/g8 directory of a given github project. This structure is used so that it is easy (but not required) for the template itself to be an sbt project. That way, an sbt plugin can be employed to locally test templates before pushing changes to github.

The easy way to start a new template project is with a giter8 template made expressly for that purpose:

$ g8 foundweekends/giter8

This will create an sbt project with stub template sources nested under src/main/g8. The file default.properties defines template fields and their default values using the Java properties file format.

Properties can be simple keys and values that replace them, but ls properties tell giter8 to query the ls.implicit.ly web API. Instead of supplying a particular version (and having to update the template with every release), specify a library and giter8 will set the value to the latest version according to ls.

The property value format is ls(library, user, repo). The second two parameters are optional, but it is a good idea to specify the github at least the user or organization that is bound to the library, in case someone else ever publishing a library module with the same name.

The n8han/giter8.g8 template itself uses this feature to refer to the latest version of the giter8 sbt plugin.

name = My Template Project
description = Creates a giter8 project template.
giter8_version = ls(giter8-plugin, n8han)

Giter8 can also resolve the latest version of projects through the Central Maven Repository.

In your default.properties, define a value as maven(groupId, artifactId) to have its latest version looked up from the central repo. Keep in mind that Scala projects are typically published with a Scala version identifier in the artifact id. So for the Unfiltered library, we could refer to the latest version as follows:

unfiltered_version = maven(net.databinder, unfiltered_2.11)

StringTemplate, wrapped by Scalasti, is the engine that applies giter8 templates, so template fields in source files are bracketed with the $ character. For example, a "classname" field might be referenced in the source as:

class $classname$ {

The template fields themselves can be utilized to define the defaults of other fields. For instance, you could build some URLs given the user's github id:

name = URL Builder
github_id=githubber
developer_url=https://github.com/$github_id$
project_url=https://github.com/$github_id$/$name;format="norm"$

This would yield the following in interactive mode:

name [URL Builder]: my-proj
github_id [githubber]: n8han
project_url [https://github.com/n8han/my-proj]:
developer_url [https://github.com/n8han]:

The name field, if defined, is treated specially by giter8. It is assumed to be the name of a project being created, so the g8 runtime creates a directory based off that name (with spaces and capitals replaced) that will contain the template output. If no name field is specified in the template, g8's output goes to the user's current working directory. In both cases, directories nested under the template's source directory are reproduced in its output. File and directory names also participate in template expansion, e.g.

src/main/g8/src/main/scala/$classname$.scala

The package field, if defined, is assumed to be the package name of the user's source. A directory named $package$ expands out to package directory structure. For example, net.databinder becomes net/databinder.

The verbatim field, if defined, is assumed to be the space delimited list of file patterns such as *.html *.js. Files matching verbatim pattern are excluded from string template processing.

Giter8 has built-in support for formatting template fields. Formatting options can be added when referencing fields. For example, the name field can be formatted in upper camel case with:

$name;format="Camel"$

The formatting options are:

upper    | uppercase       : all uppercase letters
lower    | lowercase       : all lowercase letters
cap      | capitalize      : uppercase first letter
decap    | decapitalize    : lowercase first letter
start    | start-case      : uppercase the first letter of each word
word     | word-only       : remove all non-word letters (only a-zA-Z0-9_)
Camel    | upper-camel     : upper camel case (start-case, word-only)
camel    | lower-camel     : lower camel case (start-case, word-only, decapitalize)
hyphen   | hyphenate       : replace spaces with hyphens
norm     | normalize       : all lowercase with hyphens (lowercase, hyphenate)
snake    | snake-case      : replace spaces and dots with underscores
packaged | package-dir     : replace dots with slashes (net.databinder -> net/databinder)
random   | generate-random : appends random characters to the given string

A name field with a value of My Project could be rendered in several ways:

$name$ -> "My Project"
$name;format="camel"$ -> "myProject"
$name;format="Camel"$ -> "MyProject"
$name;format="normalize"$ -> "my-project"
$name;format="lower,hyphen"$ -> "my-project"

Note that multiple format options can be specified (comma-separated) which will be applied in the order given.

For file and directory names a format option can be specified after a double underscore. For example, a directory named $organization__packaged$ will change org.somewhere to org/somewhere like the built-in support for package. A file named $name__Camel$.scala and the name awesome project will create the file AwesomeProject.scala.

Templates may be passed to the g8 command with a file:// URL, and in this case the template is applied as it is currently saved to the file system (giter8 0.6.0 +). In conjunction with the --force option which overwrites output files without prompting, you can test changes to a template as you are making them.

For example, if you have the Unfiltered template cloned locally you could run a command like this:

$ g8 file://unfiltered.g8/ --name=uftest --force

In a separate terminal, test out the template.

$ cd uftest/
$ sbt
> ~ compile

To make changes to the template, save them to its source under the .g8 directory, then repeat the command to apply the template in the original terminal:

$ g8 file://unfiltered.g8/ --name=uftest --force

Your uftest sbt session, waiting with the ~ compile command, will detect the changes and automatically recompile.

Giter8 supplies an sbt plugin for testing templates before pushing them to a github branch. If you used the n8han/giter8.g8 template recommended above, it should already be configured. If you need to upgrade an existing template project to the current plugin, you can add it as a source dependency in project/project/plugins.scala:

import sbt._
object PluginDef extends Build {
  lazy val root = Project("plugins", file(".")) dependsOn( g8plugin )
  lazy val g8plugin =
    ProjectRef(uri("git://github.com/foundweekends/giter8#0.4.4"), "giter8-plugin")
}

And settings must be applied in a build.sbt file in the project base:

seq(giter8Settings :_*)

When you enter sbt's interactive mode in the base directory of a template project that is configured to use this plugin, the action g8-test will apply the template in the default output directory (under target/sbt-test) and run the scripted test (http://eed3si9n.com/testing-sbt-plugins) for that project in a forked process. You can supply the test scripted as src/test/g8/test, otherwise >test is used. This is a good sanity check for templates that are supposed to produce sbt projects.

But what if your template is not for an sbt project?

src/main/g8/default.properties
src/main/g8/TodaysMenu.html

You can still use sbt's interactive mode to test the template. The lower level g8 action will apply default field values to the template and write it to the same target/g8 directory.

As soon as you push your template to github (remember to name the project with a .g8 extension) you can test it with the actual g8 runtime. When you're ready, add your template project to the the wiki so other giter8 users can find it.

Giter8 supplies an sbt plugin for creating and using scaffolds.

Add the following lines in project/plugins.sbt

addSbtPlugin("net.databinder.giter8" % "giter8-scaffold" % "0.6.8")

You also need to add giter8.ScaffoldPlugin.scaffoldSettings to your project:

lazy val project = Project("project").settings(giter8.ScaffoldPlugin.scaffoldSettings:_*)

Once done, the g8Scaffold command can be used in the sbt console. Use TAB completion to discover available templates.

[sample] $ g8Scaffold <TAB>
controller   global       model

The template plugin will prompt each property that needed to complete the scaffolding process:

[sample] $ g8Scaffold controller
className [Application]:

The g8 runtime looks for scaffolds in the src/main/scaffolds. Each folder inside src/main/scaffolds is a different scaffold, and will be accessible in the sbt console using the folder name. Scaffold folders may have a default.properties file to define field values, just like ordinary templates. name is again a special field name: if it exists, the scaffold will be generated into a top-level folder based on name, with subfolders following the layout of the source scaffold folder.

Once a template as been used, scaffolds are stored into <project_root>/.g8

➜  sample/.g8 
total 0
drwxr-xr-x   5 jtournay  staff   170B Aug  6 03:21 .
drwxr-xr-x  11 jtournay  staff   374B Aug  6 05:29 ..
drwxr-xr-x   4 jtournay  staff   136B Aug  6 03:21 controller
drwxr-xr-x   4 jtournay  staff   136B Aug  6 03:21 global
drwxr-xr-x   4 jtournay  staff   136B Aug  6 03:21 model

It's also possible to create your own scaffold in any sbt project by creating or modifying the .g8 folder.