the variables can not be set by a function by dot souring - powershell

Question

I want to implement a "Log" library in common.ps1 and then use dot souring to load it.
but it does not work as I expected I thought I can get the different value after calling SetLogConfiguratoion, but the value is not changed. then the "Log" function does not work becasue the log path is $null.
Do I miss-understand dot-sourcing?
write-host $g_nodeName ==> show $null
. 'C:\Test\Common.ps1'
write-host $g_nodeName ==> show "unkown"
SetLogConfiguratoion $sqlInstance (join-path $BackupShare 'RemvoeAgent.log')
write-host $g_nodeName ==> still "unkown"
Log 'ERROR' 'Test'
and Common.ps1 is as below
$g_logPath = $null
$g_nodeName = "Unknown"
function SetLogConfiguratoion
{
param
(
[Parameter(
Mandatory=$true,
HelpMessage='NodeName')]
[ValidateNotNullOrEmpty()]
[string]$NodeName,
[Parameter(
Mandatory=$true,
HelpMessage='LogPath')]
[ValidateNotNullOrEmpty()]
[string]$LogPath
)
if($LogPath.StartsWith('Microsoft.PowerShell.Core\FileSystem::'))
{
$g_logPath = $LogPath;
}
else
{
$g_logPath = 'Microsoft.PowerShell.Core\FileSystem::' + $LogPath;
}
$g_NodeName = $NodeName;
}
function Log
{
param
(
[Parameter(
Mandatory=$true,
HelpMessage='Log level')]
[ValidateNotNullOrEmpty()]
[ValidateSet(
'Error',
'Warning',
'Info',
'Verbose'
)]
[string]$level,
[Parameter(
Mandatory=$true,
HelpMessage='message')]
[ValidateNotNull()]
[string]$message
)
if($g_logPath -eq $null)
{
return
}
$time = Get-Date –format ‘yyyy/MM/dd HH:mm:ss’
$msg = "$time :: $level :: $nodeName :: $message"
Add-content $LogPath -value $message + '\n'
}

Answer 1

Dot sourcing the script will make it run in the local scope, and create the functions there, but you're still invoking the function in it's own scope. It's going to set $g_nodename in that scope. If you want all of that to run in the local scope, you need to dot source the script into the local scope to create the functions, then call the functions in the local scope (by preceding them with '. ' (note the space after the dot - that has to be there).
. SetLogConfiguratoion $sqlInstance (join-path $BackupShare 'RemvoeAgent.log')