Powershell module abort loading on unsupported hosts

Question

Glossary:

• Host: PowershellHost session
• Interactive: [Environment]::UserInteractive -eq $True

Scenario:

Create a powershell module that only will abort propertly and without error on failed condition. In this case, some commands/modules only work properly in full interactive hosts, like ISE and Console, but not in fake interactive hosts like NuGet Package Manager Console

Failed Solution:

# Add value to Powershell manifest(psd1) 
# Issue: Only supports a string for the `PowerShellHostName` property. How to specify both `ConsoleHost` and `Windows PowerShell ISE Host`? Unknown if this property supports regex, and even if it does, will the behavior change since it's not documented?
@{
    ....
    # Name of the Windows PowerShell host required by this module
    # PowerShellHostName = ''
    ....
}

Failed Solution:

# Check for interactive shell
# Issue: UserInteractive is still set in embedded shells like NuGet package manager
# console. Commands that expect user input directly often hang.
if([Environment]::UserInteractive) {
    # Do stuff, dotsource, etc
}

Failed Solution:

# Issue: returning still leaves module loaded, and it appears in Get-Module list
# Even if value is supplied for return, powershell's return statement is 'special'
# and the value is ignored
if($Host.Name -inotmatch '(ConsoleHost|Windows PowerShell ISE Host)') {
    Write-Warning "Host [$($Host.Name)] not supported, aborting"
    return 
}

Failed Solution:

# Issue: Module isn't loaded, so it can't be unloaded
if( $Host.Name -inotmatch '(ConsoleHost|Windows PowerShell ISE Host)' ) {
    Remove-Module ThisModuleName
}

Failed Solution:

# Issue: Powershell module error output is just passthrough, import-module 
# still reports success, even though $Error is has more stuff than before
if( $Host.Name -inotmatch '(ConsoleHost|Windows PowerShell ISE Host)' ) {
    Write-Error "Unsupported Host:" $Host.Name
}

Annoying solution:

# Issue: Leaves two errors on the stack, one for the throw, one for the module not 
# loading successfully
if($Host.Name -inotmatch '(ConsoleHost|Windows PowerShell ISE Host)') {
    throw "Host [$($Host.Name)] not supported, aborting"
}

Not a solution:

Force user to wrap the import every time.

Questionable Solution:

Split module into nested submodules, one for 'Common', and one for each supported Host. Use subfolder for each, and duplicate psd1 for each. Looks like it will end up being a maintainability nightmare, especially with respect to nested dependencies.

UberModule
    /ModuleCommon
        /ModuleCommon.(psd1|psm1)
    /ConsoleHostSpecific
        /ConsoleHostSpecific.(psd1|psm1)
    /IseHostSpecific
        /IseHostSpecific.(psd1|psm1)
    /etc...

Is there a better way to do this, or is the uber-module split the only way to go?

Answer 1

Take a look at the #requires keyword, it may offer a few options that you have not tried yet. I don't know if NuGet Package Manager Console has a unique ShellId or not.

#Requires –ShellId Microsoft.PowerShell

http://technet.microsoft.com/en-us/library/hh847765.aspx