Server Side : python guy

Basically, you subclass the guy class like this:

#!/usr/bin/python3 -u
from guy import Guy

class Simple(Guy):
    __doc__="""<button onclick="self.test()">test</button>"""

    def test(self):
        print("hello world")

And all declared methods will be available on client side.

Here there will be a self.test() method in client side.

Understand that a guy's class is an html page. Declared methods will be available on client side, and will be directly usable from js side.

Rendering the UI

The rendering is done after the instanciation of the class : when the client connects, or do a refresh.

Rendering with docstring

It's the simplest thing : just declare your gui/html in the docstring of your class.

class Simple(Guy):
    __doc__="""<button onclick="self.test()">test</button>"""

It's a fast way to release a simple component. But it's not adapted for larger app ;-)


here is the __doc__ declaration. Which is needed if you want to release a component like that on android (because buildozer seems to remove them, if not prefixed)

TODO : talk about template engine ! (<<var>> replaced by instance/class attributs)

Rendering with an html file

If you want to separate the UI from the code (best practice). You can put your html in a file named as the class name, in a static folder.

It's the preferable way to go, for larger app.


In this case : you should provide a tag <script src="guy.js"></script> in your html.

TODO : talk about template engine ! (<<var>> replaced by instance/class attributs)

Rendering override

Sometimes, you need to make more things, and you can do it, by overriding the render(self, path) method of your class.

For bigger app : I use vbuild to render vuejs/sfc components. (see starter-guy-vuejs, and demo)

class App(Guy):

  def render(self,path): # override default 
      with open( os.path.join(path,"app/APP.html") as fid:

      r=vbuild.render( os.path.join(path,"app/*.vue") )

      buf=buf.replace("<!-- TPLS -->",r.html)
      buf=buf.replace("/* CSS */",
      buf=buf.replace("/* JS */", r.script)      

      return buf


In this case : you should provide a tag <script src="guy.js"></script> in your response.

Guy Class

Like a normal class : you can override its constructor and set some attributs at this place. Note that, the constructor is called before the rendering : so it's the perfect place to setup some things before rendering.

TODO : Talk about returning {script: "..."}

TODO : Talk about sync/async methods.


Override this method to do thing, when a client is connected. (init method can be sync or async)


Override this method to override default rendering (see Rendering override)

path is the path to the data (where static folder sits)

If this method is not overriden : it will try to get the html from the __doc__'s string, if not ... from the static folder (guy.FOLDERSTATIC)

self.exit( returnValue=None )

Exit the app.

If you want to get a "returnValue", you can set the returned value, which will be returned in py side:

   returnValue =

cleanup( ...)

NEW in 0.7.6 event to define for cleanup things. (TODO: need better explain)

afterServerStarted( ... )

NEW in 0.7.6 event to define for starting things. (TODO: need better explain)

async self.emit( event, arg1, arg2 ... )

Call this method to emit an event to all connected clients.

It's a non-sense in app or cef mode : because there is only one client. It only got sense in server mode. Prefer the following emitMe to send an event to the gui.

async self.emitMe( event, arg1, arg2 ... )

Call this method to emit an event to the connected client.


This attribut contains the main instance (the one which starts all (which done .run())). If it's None, you are in the main instance.

async self.js

With this wrapping object, you can call js method (from the connected client) from py side, and get back a returned value :

name = await self.js.prompt("what's your name ?")


  • It can throw a guy.JSException if something is wrong on js side!
  • On py side; you'll need to await the call, even if you don't need to get back the returned value.
  • On js side; your js method can be sync or async. But your method needs to be in window scope.


Only available for guy >= 0.4.3


A place to get/set vars, which will be stored on server side, in a config.json file, where the main executable is runned. (if the guy'app is embedded in a pip/package, the config file will be stored in `~/.<package_name>.json)

To set a var 'name', in py side : = "Elton"

To get a var 'name', in py side :

name =


With this class attribut you can specify the size of your window.

This is a non-sense, in server mode. Because, it's the client/browser which determine the size of its tab.

This is a non-sense, when runned on android. Because the window is the full screen.

class Simple(Guy):
    """<button onclick="self.test()">test</button>"""
class Simple(guy.Guy):
    """<button onclick="self.test()">test</button>"""


Size may be relevant for the main window (the first started). It has no effect after a navigation or for embedded window.

Static content

guy will serve everything that is contained in a static folder, as static content.

It's really useful, when you don't embbed your html in the docstring of the class, or if you need static content like images, css files, etc ...


  • Static content should contain dots (".") in filename ! If not; current guy's version consider it must be served as dynamic content ! (it may change in the near future)

This static folder should be in the same path as your main guy class, like this :

  ├──      <- Contains class Index(guy.Guy)
  └── static
      └── Index.html

It's possible to use another for this folder, by setting guy.FOLDERSTATIC = "ui" at start.

Hook http

Guy provides an http decorator to handle specific http requests. It can be useful for a lot of things.

from guy import http

def getItem(web,number):
  web.write( "item %s"%number )

web is a Tornado's RequestHandler

TODO : talk about returning a guy window (for beautiful url)


The url catched by the hook http, can't contain dots (".") ! If there is a dot; current guy's version consider it must be served as static content ! (it may change in the near future)