Setting environments variables

I need to loop though all env vars and set their value to "" (to clear
the environment before setting a new one). But I can't get ps to
accept a variable substitution for the name?

gci env: |% { $env:$_Name=$_.Value }

Unexpected token '_Name' in expression or statement.
At line:1 char:26
+ gci env: |% { $env:$_Name= <<<< $_.Value }

Thanks,

Duncan

On Aug 4, 9:41 am, Duncan Smith <DSmith1...@googlemail.com> wrote:
> I need to loop though all env vars and set their value to "" (to clear
> the environment before setting a new one). But I can't get ps to
> accept a variable substitution for the name?
>
> gci env: |% { $env:$_Name=$_.Value }
>
> Unexpected token '_Name' in expression or statement.
> At line:1 char:26
> + gci env: |% { $env:$_Name= <<<< $_.Value }
>

Aha, needs the set-item cmdlet...

gci env: |% {$str = [string]$_.Name; set-item -path env:$str ""}

>
> Aha, needs the set-item cmdlet...
>
> gci env: |% {$str = [string]$_.Name; set-item -path env:$str ""}

....and putting it all together (just in case anyone needs to push and
pop environments) we get:

# initialize events hashtable for pushing/popping environments
$envs=@{}

function pushenv
{
# create a new hashtable of the current environment
gci env: |% {$thisenv=@{}}{$thisenv[$_.Name]=$_.Value}

# add this hashtable to the main hashtable
$envs[$envs.count] = $thisenv # add current env to envs
}

function popenv
{
# clear all vars from the current env
gci env: |% { &{param($name,$value) set-item -path env:$name
$value} $_.Name "" }

# populate current env vars from the last pushed env
$envs[$envs.count-1] |% { $_.keys |% { &{param($name,$value) set-
item -path env:$name $value -ea silentlycontinue} $_
$envs[$envs.count-1].$_ }}

# remove last pushed env from the hashtable
$envs.Remove($envs.count-1)
}

pushenv

On Aug 4, 4:41 am, Duncan Smith <DSmith1...@googlemail.com> wrote:
> I need to loop though all env vars and set their value to "" (to clear
> the environment before setting a new one). But I can't get ps to
> accept a variable substitution for the name?
>
> gci env: |% { $env:$_Name=$_.Value }
>
> Unexpected token '_Name' in expression or statement.
> At line:1 char:26
> + gci env: |% { $env:$_Name= <<<< $_.Value }
>
> Thanks,
>
> Duncan

Environment variables are held in a provider, like most things in
Powershell, so you can just treat it as such:

PS> del env:*

It's not always about the pipeline ;-)

- Oisin

On Aug 4, 8:03 am, Duncan Smith <DSmith1...@googlemail.com> wrote:
> > Aha, needs the set-item cmdlet...
>
> > gci env: |% {$str = [string]$_.Name; set-item -path env:$str ""}
>
> ...and putting it all together (just in case anyone needs to push and
> pop environments) we get:
>
> # initialize events hashtable for pushing/popping environments
> $envs=@{}
>
> function pushenv
> {
> # create a new hashtable of the current environment
> gci env: |% {$thisenv=@{}}{$thisenv[$_.Name]=$_.Value}
>
> # add this hashtable to the main hashtable
> $envs[$envs.count] = $thisenv # add current env to envs
>
> }
>
> function popenv
> {
> # clear all vars from the current env
> gci env: |% { &{param($name,$value) set-item -path env:$name
> $value} $_.Name "" }
>
> # populate current env vars from the last pushed env
> $envs[$envs.count-1] |% { $_.keys |% { &{param($name,$value) set-
> item -path env:$name $value -ea silentlycontinue} $_
> $envs[$envs.count-1].$_ }}
>
> # remove last pushed env from the hashtable
> $envs.Remove($envs.count-1)
>
> }
>
> pushenv

Alternatively, try:

"push"

$vars = gci env:

"pop"

$vars | % { set-item "env:\$($_.key)" $_.value }

;-)

- Oisin

On Aug 4, 4:38 pm, Oisin Grehan <ois...@gmail.com> wrote:
> On Aug 4, 4:41 am, Duncan Smith <DSmith1...@googlemail.com> wrote:
>
> > I need to loop though all env vars and set their value to "" (to clear
> > the environment before setting a new one). But I can't get ps to
> > accept a variable substitution for the name?
>
> > gci env: |% { $env:$_Name=$_.Value }
>
> > Unexpected token '_Name' in expression or statement.
> > At line:1 char:26
> > + gci env: |% { $env:$_Name= <<<< $_.Value }
>
> > Thanks,
>
> > Duncan
>
> Environment variables are held in a provider, like most things in
> Powershell, so you can just treat it as such:
>
> PS> del env:*
>
> It's not always about the pipeline ;-)
>
> - Oisin

A good point! I'll re-factor it for the sake of brevity.

Another question: Have you seen the CustomClass samples for Payette's
book (using the PSCustomObject ETS system)? I'm using it well, but
can't find a way to specify a constructor so that it gets called
automatically on object instantiation.

Closest I have is something like:

customclass axis {
note axisType 0
note pt @($pt)

method axis {
".ctor called"
}
}

.. $axis = newc axis
.. $axis.axis() # <- must call manually

Not very satisfying...

Thanks,

Duncan