# Kaleidoscope-HostOS The `HostOS` extension is not all that useful in itself, rather, it is a building block other plugins and extensions can use to not repeat the same guesswork and logic. The goal is to have a single place that remembers the host OS, whether set by the end-user in a Sketch, or via a macro, or some other way. This information can then be reused by other plugins. See the [Unicode][plugin:unicode] extension for an example about how to use `HostOS` in practice. [plugin:unicode]: Unicode.md ## Using the extension The extension provides a `HostOS` singleton object. ```c++ #include <Kaleidoscope.h> #include <Kaleidoscope-HostOS.h> void someFunction(void) { if (HostOS.os() == kaleidoscope::hostos::LINUX) { // do something linux-y } if (HostOS.os() == kaleidoscope::hostos::OSX) { // do something OSX-y } } KALEIDOSCOPE_INIT_PLUGINS(HostOS) void setup(void) { Kaleidoscope.setup (); } ``` ## Extension methods The extension provides the following methods on the `HostOS` singleton: ### `.os()` > Returns the stored type of the Host OS. ### `.os(type)` > Sets the type of the host OS, overriding any previous value. The type is then > stored in EEPROM for persistence. ## Host OS Values The OS type (i.e. the return type of `.os()` and the arguments to `.os(type)`) will be one of the following: - `kaleidoscope::hostos::LINUX` - `kaleidoscope::hostos::OSX` - `kaleidoscope::hostos::WINDOWS` - `kaleidoscope::hostos::OTHER` ## Focus commands The plugin provides the `FocusHostOSCommand` object, which, when enabled, provides the `hostos.type` Focus command. ### `hostos.type [type]` > Without argument, returns the current OS type set (a numeric value). > > With an argument, it sets the OS type. > > This command can be used from the host to reliably set the OS type within the firmware. ## Dependencies * [Kaleidoscope-EEPROM-Settings](EEPROM-Settings.md) ## Further reading Starting from the [example][plugin:example] is the recommended way of getting started with the extension. [plugin:example]: ../../examples/Features/HostOS/HostOS.ino