bug#59730: gdb-mi.el: Local variables reordering

[Gustaf Waldemarson <gustaf.waldemarson@gmail.com>]

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The updated patch is attached to this mail. Although I was not able to find
any reference to the GDB options that changes
how types are displayed (
https://sourceware.org/gdb/onlinedocs/gdb/Print-Settings.html#Print-Settings).
Am I just
blind? Or did you have a specific setting in mind?

Best regards,
Gustaf

Den tors 1 dec. 2022 kl 21:40 skrev Gustaf Waldemarson <
gustaf.waldemarson@gmail.com>:

> > First, if the problem is that the type names are long, maybe it will be
> > enough to truncate them without changing the order?
>
> The truncation is the main issue, although I would argue that this is also
> a good opportunity to change
> the order as well given some of the benefits of a left-to-right reading
> order, (e.g., it is easier to read and
> parse, as explained Herb Sutter^1). Other languages such as Rust/Go could
> also benefit from this. That said,
> I guess this might be a western thing, and it is hardly a hill I would die
> on, so to speak.
>
> > Also, latest version of GDB allow control on which types get shown in
> full
> > and which are shown as <...> -- did you try to use that GDB option to
> make
> > the display more easily readable?
>
> I was not aware of this. I will look into it and see if I can enable it.
> That said, there's probably benefits to having
> the option to truncate from Emacs anyways, primarily to support older
> versions of GDB.
>
> > And wouldn't it be better to truncate the string with
> > truncate-string-to-width or with string-truncate-left instead?
>
> Absolutely, I just was not aware of these (better) tools. One could even
> argue that a custom filter-function could be warranted,
> but I think that's a bit overkill right now at least.
>
> > And finally, when the type is truncated, would it be possible to add a
> > tooltip with the full name of the type, so that users who need that could
> > hover the mouse above the truncated type and see it in full?
>
> Excellent idea, that should be doable by just adding some properties to
> the strings, I'll see if I can sort these things out as well.
>
> Thanks for the feedback, I'll start working on an updated patch soon-ish
>
> ^1. See e.g.
> https://softwareengineering.stackexchange.com/questions/101978/advantages-of-a-left-to-right-language-syntax
> ^1. and https://herbsutter.com/2011/05/04/interview-on-channel-9-2/
>
> Best regards,
> Gustaf
>
> Den tors 1 dec. 2022 kl 16:45 skrev Eli Zaretskii <eliz@gnu.org>:
>
>> > From: Gustaf Waldemarson <gustaf.waldemarson@gmail.com>
>> > Date: Wed, 30 Nov 2022 23:09:14 +0100
>> >
>> > In summary, this patch does this: In gdb-mi.el mode, for local C/C++
>> variables that were previously written
>> > out:
>> >
>> > - | type | name | value|
>> >
>> > Now write them out as:
>> >
>> > - | name | type | value |
>> >
>> > Additionally, cap the string length of the name and type to
>> `gdb-locals-max-name-length` and
>> > `gdb-locals-max-type-length` respectively (new custom variables with a
>> default set to 20). I also changed the
>> > table to always left-align the values when we're printing the locals.
>> >
>> > Turns out it was really easy to fix, but I may have missed some
>> subtleties, so feel free to give it a look or
>> > start a discussion whether this is a good idea or not. I personally
>> prefer it this way since it is much easier
>> > and faster to see the values of individual variables, especially when
>> the type-info get very long.
>>
>> First, if the problem is that the type names are long, maybe it will be
>> enough to truncate them without changing the order?
>>
>> Also, latest version of GDB allow control on which types get shown in full
>> and which are shown as <...> -- did you try to use that GDB option to make
>> the display more easily readable?
>>
>> And wouldn't it be better to truncate the string with
>> truncate-string-to-width or with string-truncate-left instead?
>>
>> And finally, when the type is truncated, would it be possible to add a
>> tooltip with the full name of the type, so that users who need that could
>> hover the mouse above the truncated type and see it in full?
>>
>> Thanks.
>>
>

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From 4f238c72acbc15eaee7ed7cd19c3aeac19a55a7b Mon Sep 17 00:00:00 2001
From: Gustaf Waldemarson <gustaf.waldemarson@gmail.com>
Date: Tue, 29 Nov 2022 23:40:23 +0100
Subject: [PATCH] gdb-mi.el: Swap type and name column in locals.

Additionally, truncate the column lengths and add the full length as a
help-text (tooltip).
---
 lisp/progmodes/gdb-mi.el | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/lisp/progmodes/gdb-mi.el b/lisp/progmodes/gdb-mi.el
index e8d8f9104e4..197d133f0ee 100644
--- a/lisp/progmodes/gdb-mi.el
+++ b/lisp/progmodes/gdb-mi.el
@@ -4355,6 +4355,19 @@ gdb-locals-value-limit
   :group 'gud
   :version "29.1")
 
+(defcustom gdb-locals-max-type-length 20
+  "Maximum number of character to display in the local variables type column."
+  :type 'integer
+  :group 'gud
+  :version "30.0")
+
+(defcustom gdb-locals-max-name-length 20
+  "Maximum number of character to display in the local variables name column."
+  :type 'integer
+  :group 'gud
+  :version "30.0")
+
+
 (defvar gdb-locals-values-table (make-hash-table :test #'equal)
   "Mapping of local variable names to a string with their value.")
 
@@ -4431,11 +4444,16 @@ gdb-locals-handler-custom
                                             help-echo "mouse-2: edit value"
                                             local-map ,gdb-edit-locals-map-1)
                                value))
+        (setf (gdb-table-right-align table) t)
         (gdb-table-add-row
          table
          (list
-          (propertize type 'font-lock-face font-lock-type-face)
-          (propertize name 'font-lock-face font-lock-variable-name-face)
+          (propertize (string-truncate-left name gdb-locals-max-name-length)
+                      'font-lock-face font-lock-variable-name-face
+                      'help-echo name)
+          (propertize (string-truncate-left type gdb-locals-max-type-length)
+                      'font-lock-face font-lock-type-face
+                      'help-echo type)
           value)
          `(gdb-local-variable ,local))))
     (insert (gdb-table-string table " "))
-- 
2.34.1