C-like macro expansion in PowerShell

Question

Recently I've started fiddling around with PowerShell, and I bumped into an issue with running .jar files. Simply put, I'm using plantuml and I'd like to simply have a "plantuml" command to run it. Normally, running the program would be done by typing. java -jar C:\Users\Name\Documents\WindowsPowerShell\Commands\plantuml.jar. This is of course quite a handful, and I'd like to shorten this to simply plantuml.

My current work-around is the following function: function plantuml($UmlPath, $ImgPath) { java -jar C:\Users\Name\Documents\WindowsPowerShell\Commands\plantuml.jar $UmlPath $ImgPath } However, I cannot pass any parameters to the .jar file like this, because Powershell intercepts them and interprets them as function parameters. A current workaround for this is by wrapping them in quotation marks, but I find this ugly and I often forget.

Is there any way to simply be able to type plantuml so that PowerShell expands it to java -jar C:\Users\Name\Documents\WindowsPowerShell\Commands\plantuml.jar? The only similar question I found was this one, but it doesn't appear to have an actual answer.

if you need to pass additional parameters you can add an additional param to your function, something like `$params` and send it a string representing the parameters you want added to the end of the command, would end up with a bit of a strange syntax but as long as you were aware of it it would at least save you a bunch of typing. — Mike Garuccio, Dec 02 '16 at 19:18
The advice in this article may be helpful to you: [Windows IT Pro - Running Executables in PowerShell](http://windowsitpro.com/powershell/running-executables-powershell). — Bill_Stewart, Dec 02 '16 at 21:41
Also, please give an example of what you mean by "I cannot pass any parameters to the .jar file like this, because Powershell intercepts them and interprets them as function parameters." — Bill_Stewart, Dec 02 '16 at 21:44
Example: a way to test whether plantuml is working is by passing the -testdot parameter to the .jar, e.g. `java -jar C:\Users\Name\Documents\WindowsPowerShell\Commands\plantuml.jar -testdot`. However, if I do this with the current function, PowerShell sees "-testdot" as a parameter to my actual function instead of to the .jar file, so that the .jar file never actually receives the parameter. — PostLee, Dec 02 '16 at 22:26
Thank you Bill_Stewart, a combination of your article and TesselatingHeckler's answer solved my issue! — PostLee, Dec 02 '16 at 22:51

score 0 · Accepted Answer · answered Dec 02 '16 at 19:20

0

I don't have plantuml or anything similar to test with, but you can get all the parameters passed to a function with the $args variable, so this approach might work:

function plantuml {

  # Array of your default arguments to Java.exe to start plantuml
  $arguments = @('-jar',
                 'C:\Users\Name\Documents\WindowsPowerShell\Commands\plantuml.jar') 

  # All arguments passed to this function, umlpath, imgpath, and anything else
  # are in the special variable $args, add those into the array as well.
  $arguments += $args

  Start-Process Java -ArgumentList $arguments
}

answered Dec 02 '16 at 19:20

TessellatingHeckler

27,511
4
48
87

I think this answer is going in the right direction! However, the expected behaviour of running plantuml -testdot would be that the output is in the PowerShell terminal itself, whereas now it appears to open a new terminal for the Java process, after which it immediately closes again. The biggest downside of this is that I can't see the printed result, because the window immediately closes. Any ideas? – PostLee Dec 02 '16 at 22:36
Update: passing the -NoNewWindow parameter fixed that, but now the terminal doesn't wait for plantuml to finish and the output is in a weird place (i.e. if I start writing, I overwrite the output). I tried adding -Wait, but that didn't seem to have any effect. *EDIT*: Please ignore the above, the -Wait parameter suddenly worked, guess I forgot to reload my PowerShell. Thank you for your help! – PostLee Dec 02 '16 at 22:47
@postlee - NoNewWindow is a good catch, and I'm glad you got -Wait working or I'd have had no clue what else to suggest for that :) – TessellatingHeckler Dec 04 '16 at 00:18

C-like macro expansion in PowerShell

1 Answers1