On 2016-08-28 06:59 PM, Lex Trotman wrote:
On 29 August 2016 at 10:47, Matthew Brush <mbr...@codebrainz.ca> wrote:
[...]

"Registration" - the act (ie. function call) of an ft-plugin declaring its
interest in providing a feature for a filetype. An ft-plugin can register to
provide one or more features for one or more filetypes.

I think the registration data should go in the plugin data file that
Thomas added, not require plugins to be loaded to register, otherwise
all language plugins will be loaded at all times just so they can call
the function to be registered.


That's a thought. I think the plugin data file you refer to may only be for the libpeas proxy plugin which is not part of Geany (yet).

IIUC, at least when the plugin manager is opened, Geany loads all of the plugin DLLs anyway. Plugins could register their providers at `geany_load_module()`-time before they're actually initialized. Needs more consideration.


----

In this design, a new module (c/h file) would be added to manage the
filetype plugins and which features they provide for which filetypes. A
mapping (ex. GHashTable) could be used to map from Filetype to a list (ex.
GQueue) of data describing the needed information for a registered provider.
The list would be ordered in the same order as registration and could also
be re-ordered by the user using a GUI (more on this below).

Would need to ensure plugin loading will re-load in the
original/specified order, IIRC it currently re-loads in alpha order.


Yeah, possibly storing this info in separate ftplugin-specific keys in the config file.


The order of the list of plugins registered to provide a feature for a given
feature/filetype pair would determine the priority given when Geany asks the
provider to perform its function. The callback functions could return a
boolean telling Geany whether the provider performed its function or whether
it should try the next provider in the list, similar to many GTK+ callbacks.
If no provider performs its function, or there are no providers registered
for a given feature/filetype, then Geany would take its existing code path
to provide the feature itself.

This makes sense, but so does Colombans desire for plugins to be able
to improve on the work of other plugins so you don't have to have all
plugins re-implement the basic functionality.  Not immediately sure
how to reconcile these two options, unless Colombans desire is
provided by having the dependent plugin have to call the basic plugin
function directly, so its not Geany's problem.


That's the idea with boolean results, a plugin could actually provide the feature but return `FALSE` and Geany would call the next provider to perform the feature as well. It's kind of like a poor-man's inheritance.



When a plugin registers its intent to provide a feature (or perhaps after it
has registered all the features it wishes to provide), Geany could check
whether there is already another plugin providing this feature. Geany could
ask the user if they would like to resolve the conflict, and if they would,
then it could show a management dialog (see attachment for mockup), allowing
the user to control the priority of the plugin's provider for a given
feature/filetype by moving them up or down in a list, and possibly being
able to completely disable a provider entirely (via a checkbox in the list
or something).

Not sure about this dialog happening automatically, think it would
need a "Shut TF up" option, and also be quiet at re-load.  But
certainly providing the advanced user control of the providers is
fine.


Yeah, I thought it might be annoying too. Will need experimentation.



To enable Geany to use the providers, in the existing code just before it's
about to provide the feature itself as it does now, we could insert a
check/call to try the ft-plugin providers.

This may require some unwinding of the spaghetti to clearly identify
the beginning of a "feature" and ensure it happens in one place.  Some
places there is stuff split between different callbacks depending on
how the feature was triggered.


Most likely yeah. In some cases though, it might be as simple as sticking an "if" statement at the beginning of a single function with an early return.


 If nobody performed the feature,
then it would continue to the existing code path. This should limit the
number of changes needed to Geany. Some features would necessarily require
more changes, for example syntax highlighting would require Geany to switch
from the Scintilla lexer to the container lexer and back as plugins
start/stop providing the feature. It will require care for features that are
activated often to ensure minimal performance degradation when looking up
and calling into the provider, as this would happen in the main code paths
(unless someone has a better way).

It is always a requirement for plugins to not hog or block the main
thread, they can do that by other threads or separate processes, but
its their problem and not unique to FT plugins.


I meant in Geany's code. The way I was thinking will require at least to perform a hash lookup, walk one or more elements of a linked list, perform an indirect function call, etc. I don't think there's any point in prematurely optimizing it, I just wanted to point out that it might come with some cost, especially where done frequently.


Hopefully I have described enough details of my proposed design to allow
everyone to understand what I mean. If there's any questions or suggestions,
please let me know.

What is missing is how the FT plugins get loaded in the first place so
they can register, if the user can control that from the PM GUI, or if
these plugins are controlled from your GUI only (my preference).  If
the FT plugins are loaded via a different path and don't appear in the
PM that may solve the order issue as well.


At least initially, I think when the plugins are activated they could register their providers. The user would just check the plugin in the plugin manager dialog as usual. In the future it could be at `geany_load_module()`-time, some separate GUI, or a plugin data file, statically as you mentioned above. It could even be done using the filetype.* configuration files. IMO, we should start with what's as simple as possible to perform the function.

Cheers,
Matthew Brush



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