# gitk's back button broken (Refactor per-line part of getblobdiffline and its support)

3 messages from 2013-12-16 to 2013-12-19. Participants: Johannes Sixt, Thomas Rast.
Thread: https://gitlist.dev/t/35533

## Johannes Sixt, 2013-12-16 13:56

Subject: gitk's back button broken (Refactor per-line part of getblobdiffline and its support)
Message-ID: <52AF0688.3070104@viscovery.net>
URL: https://gitlist.dev/e/52AF0688.3070104%40viscovery.net

```
To reproduce, start gitk in any repository, click a commit, then the
"back" button (left-pointing arrow button) or type Alt+Cursor-Left. The
error I get is this:

can't use non-numeric string as operand of "!"
can't use non-numeric string as operand of "!"
    while executing
"if {!$ateof} {
	set nlines [expr {[winfo height $ctext]
			  / [font metrics textfont -linespace]}]
	if {[$ctext compare "$target_scrollpos + $nlines ..."
    (procedure "maybe_scroll_ctext" line 5)
    invoked from within
"maybe_scroll_ctext ateof"
    (procedure "blobdiffmaybeseehere" line 6)
    invoked from within
"blobdiffmaybeseehere [eof $bdf]"
    (procedure "getblobdiffline" line 15)
    invoked from within
"getblobdiffline filef5ec60 5de460a2cfdd4acbadd41355a5b34dc69e93b89e"
    ("eval" body line 1)
    invoked from within
"eval $script"
    (procedure "dorunq" line 11)
    invoked from within
"dorunq"
    ("after" script)

After dismissing the error, gitk is still responsive, but does not show
diffs anymore.

The error bisects to 5de460a2c (gitk: Refactor per-line part of
getblobdiffline and its support) which is already merged downstream into git.

Could you please have a look?

-- Hannes

```

## Johannes Sixt, 2013-12-19 07:14

Subject: [PATCH] gitk: Fix typo in proc blobdiffmaybeseehere
Message-ID: <52B29CB8.8090304@viscovery.net>
URL: https://gitlist.dev/e/52B29CB8.8090304%40viscovery.net
In-Reply-To: <52AF0688.3070104@viscovery.net>

```
From: Johannes Sixt <j6t@kdbg.org>

The recent 5de460a2 (Refactor per-line part of getblobdiffline and its
support) introduced blobdiffmaybeseehere, and accidentally forgot the '$'
to access the parameter as a TCL variable. This resulted in a failing
"Back" button with the error

can't use non-numeric string as operand of "!"
    while executing
"if {!$ateof} {
	set nlines [expr {[winfo height $ctext]
			  / [font metrics textfont -linespace]}]
	if {[$ctext compare "$target_scrollpos + $nlines ..."
    (procedure "maybe_scroll_ctext" line 5)

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
Am 12/16/2013 14:56, schrieb Johannes Sixt:
> To reproduce, start gitk in any repository, click a commit, then the
> "back" button (left-pointing arrow button) or type Alt+Cursor-Left. The
> error I get is this:
> 
> can't use non-numeric string as operand of "!"

It turns out to be just a simple typo.

-- Hannes

 gitk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gitk b/gitk
index 33c3a6c..1f14796 100755
--- a/gitk
+++ b/gitk
@@ -7922,7 +7922,7 @@ proc blobdiffmaybeseehere {ateof} {
     if {$diffseehere >= 0} {
 	mark_ctext_line [lindex [split $diffseehere .] 0]
     }
-    maybe_scroll_ctext ateof
+    maybe_scroll_ctext $ateof
 }
 
 proc getblobdiffline {bdf ids} {
-- 
1.8.5.1.1587.g3845a3d

```

## Thomas Rast, 2013-12-19 23:16

Subject: Re: [PATCH] gitk: Fix typo in proc blobdiffmaybeseehere
Message-ID: <87ob4cctxx.fsf@linux-1gf2.Speedport_W723_V_Typ_A_1_00_098>
URL: https://gitlist.dev/e/87ob4cctxx.fsf%40linux-1gf2.Speedport_W723_V_Typ_A_1_00_098
In-Reply-To: <52B29CB8.8090304@viscovery.net>

```
Johannes Sixt <j.sixt@viscovery.net> writes:

> can't use non-numeric string as operand of "!"
>     while executing
> "if {!$ateof} {
> 	set nlines [expr {[winfo height $ctext]
> 			  / [font metrics textfont -linespace]}]
> 	if {[$ctext compare "$target_scrollpos + $nlines ..."
>     (procedure "maybe_scroll_ctext" line 5)
>
> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
> Am 12/16/2013 14:56, schrieb Johannes Sixt:
>> To reproduce, start gitk in any repository, click a commit, then the
>> "back" button (left-pointing arrow button) or type Alt+Cursor-Left. The
>> error I get is this:
>> 
>> can't use non-numeric string as operand of "!"
>
> It turns out to be just a simple typo.
[...]
> -    maybe_scroll_ctext ateof
> +    maybe_scroll_ctext $ateof
>  }

Ew.  Sorry about that!

It's very polite of you to call it a typo, but I think it's safe to
blame it on my lack of practice in Tcl :-)

-- 
Thomas Rast
tr@thomasrast.ch

```