106 lines
4.2 KiB
Text
106 lines
4.2 KiB
Text
Overview
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========
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NOTE: This is not an introduction to XMPP, but to poezio
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Global overview
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---------------
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Poezio is an application that has three main layers, mostly separated in three
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different python modules: _core_, _tabs_, and _windows_. An UML diagram of
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Poezio would be inneficient, cluttered, or incomplete, so there is none, if
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that bugs you.
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image::../../images/layers.png["The application layers", title="Layers"]
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_Core_ is mostly a “global” object containing the state of the application at
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any time, it contains the global commands, the xmpp event handlers, the list
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of open tabs, etc. Most objects in poezio have a self.core attribute
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referencing the _Core_ (it’s a singleton, so there is never more than one
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instance). _Core_ also contains the main loop of the application, which then
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dispatchs the I/O events (keypress) to the appropriate methods.
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But the main loop is not the most important thing in poezio; because it is an
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IM client, it is essentially event-driven. The event part is handled by
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SleekXMPP, which is the library we chose after moving away from xmpppy.
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_Tabs_ are the second layer of poezio, but the first dealing with the UI: each
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_Tab_ is a layout of several _windows_, it contains tab-specific commands,
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tab-specific keybinds, and it has methods in order for core to
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interact with it, and some methods are only proxies for the methods of a
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_window_
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Example scenario: If someone presses the key PageUp, then Core will call the
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appropriate method on the current _Tab_, which will in turn, if it implements the
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method (inherited empty from the Tab class), call a scrolling method from the
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appropriate _window_.
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All tabs types inherit from the class _Tab_, and the _Tabs_ featuring
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chat functionnality will inherit fro _ChatTab_ (which inherits from _Tab_).
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Examples of _Tabs_: MUCTab, XMLTab, RosterTab, MUCListTab, etc…
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Event handlers
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--------------
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The events handlers are registered right at the start of poezio, and then
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when a matching stanza is received, the handler is called in a separate thread
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from the main loop. The handlers are in _Core_, and then they call the
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appropriate methods in the corresponding _tabs_.
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Example scenario: if a message is received from a MUC, then the _Core_ handler
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will identify the _Tab_, and call the relevant handler from this _Tab_, this tab
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will in turn, add the message to the buffer, which will then add it to the
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relevant _windows_.
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NOTE: All the _windows_ that deal with received or generated text are linked
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to a _text_buffer_, in order to rebuild all the display lines from an the
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sources if necessary. This also enables us to have several _windows_
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presenting the same text, even if they are not of the same size and layout.
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Commands and completion
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-----------------------
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Commands are quite straightforward: those are methods that take a string as a
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parameter, and they do stuff.
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From an user point of view, the methods are entered like that:
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==================================
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/command arg1 arg2
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or
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/command "arg1 with spaces" arg2
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==================================
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However, when creating a command, you wil deal with _one_ str, no matter what.
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There are utilities to deal with it (common.shell_split), but it is not always
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necessary. Commands are registered in the _commands_ dictionnary of a tab
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structured as key (command name) -> tuple(command function, help string, completion).
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Completions are a bit tricky, but it’s easy once you get used to it:
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They take an _Input_ (a _windows_ class) as a parameter, named the_input
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everywhere in the sources. To effectively have a completion, you have to call
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_the_input.auto_completion()_ at the end of the function.
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*the_input.auto_completion(completion_list, after='', quote=True)*:
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Set the input to iterate over _completion_list_ when the user hits tab, insert
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_after_ after the completed item, and surround the item with double quotes or
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not.
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There is no method to find the current argument in the input (although the
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feature is planned), so you have to assume the current argument is the last,
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and guess it by splitting the string an checking for end-space.
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You can look for examples in the sources, all the possible cases are
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covered (single-argument, complex arguments with spaces, several arguments,
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etc…)
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