On Fri, Feb 17, 2012 at 4:50 PM, Uli Schlachter <psyc...@znc.in> wrote:
>> +function table.apply(t, filter, callback)
>> +    for _, i in pairs(t) do
>> +        if filter(i) and callback(i) == false then return end
>> +    end
>> +end
>
> Dunno how often something like that is needed. Only thing which I can think of
> right would be awful.rules.

Rules, together with menu and naughty, is my favorite part :).

> Anyway, what do you think about also using this for searching?

The previous patch series was headed in the wrong direction -- I was
dressing up _for_ without any significant gains.  The attached patches
better reflect what I was trying to do.  Something like:

local urxvt = function (c) return awful.rule.match(c, {class = "URxvt"))
for c in awful.client.cycle(urxvt) do
  awful.client.floating.set(c)
end

Now you can do this using rules, but my function adds a more dynamic,
natural, and concise feel to it.  You can use it create menus on the
fly.  Makes it more fun to script awesome from the shell with
awesome-client:

local filter = function (c)
  return awful.rule.match(c, {class = "URxvt", except = {instance = "term"}})
end
for c in awful.client.cycle(urxvt) do
  c:kill()
end

My own selfish reason to push this into awful is to simplify run or
raise implementation.  I think it is a nice to have feature but people
(including myself) have all sort of complicated implementations (just
see the wiki page) which causes new users to shy away from it.

>> The functionality to terminate matching by returning false can be
>> useful if one wants to take an action on only the first matching item,
>> like raising a client, etc.
>
> Hm. For something like this, my table.find() might be a better fit. Possibly.

With the new implementation, we won't really need it, because all
awful is providing is an easy way to iterate a select list of clients.
 Do whatever you want in the body of 'for': break iteration, return
from function ... whatever suits the need.

-- 
Anurag Priyam
From 3106c952a52d80c3ef30e7cc0c37eacb1e84dcca Mon Sep 17 00:00:00 2001
From: Anurag Priyam <anurag08pri...@gmail.com>
Date: Fri, 17 Feb 2012 02:30:41 +0530
Subject: [PATCH 1/2] add awful.util.table.cycle to iterate through elements
 that match given condition

This will help writing concise code when one wants to apply a function to
(read, take some action) on a select list of elements in a table (of say,
clients and tags).

Signed-off-by: Anurag Priyam <anurag08pri...@gmail.com>
---
 lib/awful/util.lua.in |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/lib/awful/util.lua.in b/lib/awful/util.lua.in
index 1c719a7..026e7d8 100644
--- a/lib/awful/util.lua.in
+++ b/lib/awful/util.lua.in
@@ -367,4 +367,25 @@ function table.clone(t)
     return c
 end
 
+---
+-- Returns an iterator to cycle through, starting from the first element or the
+-- given index, all elments of a table that match a given criteria.
+-- @param t      the table to iterate
+-- @param filter a function that returns true to indicate a positive match
+-- @param start  what index to start iterating from.  Default is 1 (=> start of
+-- the table)
+function table.cycle(t, filter, start)
+    local count  = 0
+    local index  = start or 1
+    local length = #t
+
+    return function ()
+        while count < length do
+            local item = t[index]
+            index = cycle(#t, index + 1)
+            count = count + 1
+            if filter(item) then return item end
+        end
+    end
+end
 -- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80
-- 
1.7.9

From a1256797c2c292edd894bfa4c6f0bbac952e1ba5 Mon Sep 17 00:00:00 2001
From: Anurag Priyam <anurag08pri...@gmail.com>
Date: Fri, 17 Feb 2012 02:32:28 +0530
Subject: [PATCH 2/2] add awful.client.cycle to iterate through clients that
 match a given condition

A common use case is to cycle through clients that match a given rule and take
certain action on them: raise, set or get property, etc.; see usage example in
the docs.

Signed-off-by: Anurag Priyam <anurag08pri...@gmail.com>
---
 lib/awful/client.lua.in |   24 ++++++++++++++++++++++++
 1 files changed, 24 insertions(+), 0 deletions(-)

diff --git a/lib/awful/client.lua.in b/lib/awful/client.lua.in
index 2d5ec45..aae9144 100644
--- a/lib/awful/client.lua.in
+++ b/lib/awful/client.lua.in
@@ -862,6 +862,30 @@ function property.set(c, prop, value)
     c:emit_signal("property::" .. prop)
 end
 
+---
+-- Returns an iterator to cycle through, starting from the client in focus or
+-- the given index, all clients that match a given criteria.
+-- @param filter a function that returns true to indicate a positive match
+-- @param start  what index to start iterating from.  Defaults to using the
+-- index of the currently focused client.
+-- @usage e.g.: un-minimize all urxvt instances
+-- <p><code>
+-- local urxvt = function (c) <br/>
+-- return awful.rules.match(c, {class = "URxvt"}) <br/>
+-- end <br/>
+-- </br>
+-- for c in awful.client.cycle(urxvt) do <br/>
+-- c.minimized = false <br/>
+-- end <br/>
+--
+-- </code></p>
+function cycle(filter, start)
+    local clients = capi.client.get()
+    local focused = capi.client.focus
+    local start   = start or util.table.hasitem(clients, focussed)
+    return util.table.cycle(clients, filter, start)
+end
+
 -- Register standards signals
 capi.client.add_signal("property::floating_geometry")
 capi.client.add_signal("property::floating")
-- 
1.7.9

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