Do not update WindowTitle at all in prompt func if setting is $null

[rkeithhill]

We used to restore the previousWindowTitle but this had the effect of
always updating the WindowTitle with a fixed string - whatever we
captured in $PreviousWindowTitle.

However, we still restore the original window title when the module is
removed. But we only do this if the module is configured to supply the
window title.

Rename variable to make its intent clearer.

Fixes #594

[dahlbyk]

Thanks for getting this change going! I think there's enough complexity here that we're better off moving it out of the psm1. Thoughts?

[dahlbyk]

If we're going to let $GitPromptSettings.WindowTitle = $false really suppress touching WindowTitle, we might as well avoid this, too.

Thoughts on moving this whole block into a Test-WindowTitle function (in Utils.ps1)? I figure that function would close over a script variable that's $null until we actually need to probe, at which point it would probe and remember for future checks.

The check below would then be:

if ($settings.WindowTitle -and (Test-WindowTitle)) {
    # ...

This would short-circuit the probe until $settings.WindowTitle isn't falsey.

[rkeithhill]

But when $settings.WindowTitle isn't falsey, we would be doing this "writable" check during every prompt eval - effectively setting the title three times.

I think it is better to do this check once during module load but I'm fine with creating a function in Utils.ps1 so we'd have:

$IsAdmin = Test-Administrator
$IsWindowTitleWritable = Test-WindowTitleIsWritable

[dahlbyk]

Does this actually need to be global? Could it be script-scoped alongside $HostSupportsSettingWindowTitle, with a corresponding Reset-WindowTitle to use in OnRemove?

[rkeithhill]

Yeah, it could be script scoped.

[dahlbyk]

While we're at it, should this whole block move into a Set-WindowTitle function?

[rkeithhill]

Sure, but we'd need to export it from the module to make it callable from the prompt func. How about Reset-WindowTitle - does it need to be exported or would we be the only caller in the OnRemove event handler.

[dahlbyk]

While we're at it, should this whole block move into a Set-WindowTitle function?

Sure, but we'd need to export it from the module to make it callable from the prompt func.

I was pretty sure this wasn't the case, and my experiment to find out may have gone a bit far. Anyway, the new commits here seem to work as expected and the module is much cleaner.

[rkeithhill]

👍

[rkeithhill]

Looks good! My daughter just got back from her choir trip to Europe so didn't have time to tackle this last night. Thanks!! Go ahead and merge whenever you're ready.

I have to say I'm a bit surprised the scriptblock we assign to the global func prompt can see that non-exported command. I was assuming the scriptblock closed over the variables it used. TIL that scriptblock seems to have access to module scope. :-)