Re: svn commit: r329609 - head/stand/lua

[Alexander Nasonov]

Ian Lepore wrote:
> On Mon, 2018-02-19 at 22:29 +, Kyle Evans wrote:
> > 
> > +???-- Swap the first two menu entries
> > +???menu_entries[1], menu_entries[2] = menu_entries[2],
> > +?? menu_entries[1];
> > ?
> 
> IMO, this is the sort of unreadable insanity that comes from having
> inflexible rules about line-wrapping which trump readability. ?The
> original code could be easily understood. ?The suggested replacement,?
> 
> menu_entries[1], menu_entries[2] =
> ? ? menu_entries[2], menu_entries[1]
> 
> Was also pretty readable, although not as much as it would be if it
> were all on one line. ?But splitting the line at the whitespace nearest
> to 80 columns just creates an unreadable mess for the insignificant
> virtue of following some arbitrary rule. ?(Which is why I very often
> ignore that rule and split lines at the point < 80 which makes the most
> sense for understanding the code, even if that means splitting at
> column 30.)

+1

Other possibilities are:

 - moving code to a helper function often removes extra indentation
 - shorter identifiers (e.g. as a side effect of moving code to a helper
   function)

local function swap_1_2(t) t[1], t[2] = t[2], t[1] end

swap_1_2(menu_entries)

  or 

local function swap(t, i, j) t[i], t[j] = t[j], t[i] end

swap(menu_entries, 1, 2)
-- 
Alex
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Re: svn commit: r329609 - head/stand/lua

[Kyle Evans]

On Mon, Feb 19, 2018 at 4:37 PM, Ian Lepore  wrote:
> On Mon, 2018-02-19 at 22:29 +, Kyle Evans wrote:
>>
>> +   -- Swap the first two menu entries
>> +   menu_entries[1], menu_entries[2] = menu_entries[2],
>> +   menu_entries[1];
>>
>
> IMO, this is the sort of unreadable insanity that comes from having
> inflexible rules about line-wrapping which trump readability.  The
> original code could be easily understood.  The suggested replacement,
>
> menu_entries[1], menu_entries[2] =
> menu_entries[2], menu_entries[1]
>
> Was also pretty readable, although not as much as it would be if it
> were all on one line.  But splitting the line at the whitespace nearest
> to 80 columns just creates an unreadable mess for the insignificant
> virtue of following some arbitrary rule.  (Which is why I very often
> ignore that rule and split lines at the point < 80 which makes the most
> sense for understanding the code, even if that means splitting at
> column 30.)
>

Right, perhaps we should clarify this while the opportunity is ripe
for style.lua(9) into something more like "80 columns are preferred,
wrapping may occur much earlier than 80 columns." I blindly followed
it here because we hadn't discussed any exception to it previously,
but I think we're more likely in Lua to run into scenarios where the
current guideline just isn't appropriate.
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Re: svn commit: r329609 - head/stand/lua

[Ian Lepore]

On Mon, 2018-02-19 at 22:29 +, Kyle Evans wrote:
> 
> +   -- Swap the first two menu entries
> +   menu_entries[1], menu_entries[2] = menu_entries[2],
> +   menu_entries[1];
>  

IMO, this is the sort of unreadable insanity that comes from having
inflexible rules about line-wrapping which trump readability.  The
original code could be easily understood.  The suggested replacement, 

menu_entries[1], menu_entries[2] =
    menu_entries[2], menu_entries[1]

Was also pretty readable, although not as much as it would be if it
were all on one line.  But splitting the line at the whitespace nearest
to 80 columns just creates an unreadable mess for the insignificant
virtue of following some arbitrary rule.  (Which is why I very often
ignore that rule and split lines at the point < 80 which makes the most
sense for understanding the code, even if that means splitting at
column 30.)

-- Ian

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svn commit: r329609 - head/stand/lua

[Kyle Evans]

Author: kevans
Date: Mon Feb 19 22:29:16 2018
New Revision: 329609
URL: https://svnweb.freebsd.org/changeset/base/329609

Log:
  stand/lua: Cache swapped menu, and don't create locals for swapping
  
  Building the swapped welcome menu (first two items swapped) is kind of a
  sluggish, because it requires a full (recrusive) shallow copy of the welcome
  menu. Cache the result of that and re-use it later, instead of building it
  everytime.
  
  While here, don't create temporary locals just for swapping. The following
  is just as good:
  
  x, y = y, x;
  
  Reported by:  Alexander Nasonov  (swapping)

Modified:
  head/stand/lua/menu.lua

Modified: head/stand/lua/menu.lua
==
--- head/stand/lua/menu.lua Mon Feb 19 22:22:35 2018(r329608)
+++ head/stand/lua/menu.lua Mon Feb 19 22:29:16 2018(r329609)
@@ -138,17 +138,22 @@ menu.welcome = {
local menu_entries = menu.welcome.all_entries;
-- Swap the first two menu items on single user boot
if (core.isSingleUserBoot()) then
+   -- We'll cache the swapped menu, for performance
+   if (menu.welcome.swapped_menu ~= nil) then
+   return menu.welcome.swapped_menu;
+   end
-- Shallow copy the table
menu_entries = core.shallowCopyTable(menu_entries);
 
-   local multiuser = menu_entries[1];
-   local singleuser = menu_entries[2];
+   -- Swap the first two menu entries
+   menu_entries[1], menu_entries[2] = menu_entries[2],
+   menu_entries[1];
 
-   multiuser.name = multiuser.alternate_name;
-   singleuser.name = singleuser.alternate_name;
-
-   menu_entries[2] = multiuser;
-   menu_entries[1] = singleuser;
+   -- Then set their names to their alternate names
+   menu_entries[1].name, menu_entries[2].name =
+   menu_entries[1].alternate_name,
+   menu_entries[2].alternate_name;
+   menu.welcome.swapped_menu = menu_entries;
end
return menu_entries;
end,
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