If I run a Python script from Powershell via the call operator ($val = & python myscript.py) - How can I pass in an array to $val from Python?

Here's a sample script:

import os
import sys
import pathlib
import json
from contextlib import redirect_stderr
from fontTools import ttLib
from fontmeta import FontMeta
# Check for commandline argument
if len(sys.argv) == 1:
print('No argument was supplied.')
exit(0)
fontfile = sys.argv[1]
def font_name(font_path, name_idx):
font = ttLib.TTFont(font_path, ignoreDecompileErrors=True)
with redirect_stderr(None):
names = font['name'].names
details = {}
for x in names:
if x.langID == 0 or x.langID == 1033:
try:
details[x.nameID] = x.toUnicode()
except UnicodeDecodeError:
details[x.nameID] = x.string.decode(errors='ignore')
# details[4] = Full Name
# details[1] = Family Name
# details[2] = Style Name
return details[name_idx]
meta_instance = FontMeta(fontfile)
metadata = meta_instance.get_full_data()
fontFullName           = font_name(fontfile,4)
fontFamily             = font_name(fontfile,1)
fontStyle              = font_name(fontfile,2)
fontVers               = metadata[5]['value'];
fontVers               = fontVers.replace('Version ',"v")
fontLang               = metadata[1]['language']['value'];
fontUniqueID           = metadata[3]['value']
fontPostscriptName     = metadata[6]['value']
fontPostscriptEncoding = metadata[6]['encoding']['value']
fontDesigner           = metadata[9]['value']
fontLicenseURL         = metadata[14]['value']
print('Full Name:     ' + fontFullName)
print('Family:        ' + fontFamily)
print('Style:         ' + fontStyle)
print('Version:       ' + fontVers)
print('Language:      ' + fontLang)
print('UniqueID:      ' + fontUniqueID)
print('License URL:   ' + fontLicenseURL)
print('Font Designer: ' + fontDesigner)

Output:

Full Name:     Sharp Sans Bold
Family:        Sharp Sans
Style:         Bold
Version:       v1.001
Language:      English/United States
UniqueID:      1.001;2016;SHRP;SharpSans-Bold
License URL:   http://www.sharptype.co
Font Designer: Lucas Sharp

ps1:

& "D:\Dev\Python\00 VENV\FontTools\Scripts\Activate.ps1"
$val = python "D:\Dev\Python\Font Scripts\GetFontInfo.py" "D:\Fonts\00 Test\SharpSans-Bold.otf"
Write-Host "`$val:" $val -ForegroundColor Green

Right now the Python code is just printing values. My PS script is echoing the printed values as a string. Is there a way to pass these values to powershell other than just printing them - I.E. as an array?

Or should I return JSON and parse it in PowerShell?

Any help appreciated.

When PowerShell invokes an external program, it streams the individual lines of its stdout output one by one to PowerShell's pipeline.

If you capture this stream via assignment to a variable:

• two or more lines become an array (of type [object[]]) storing the lines.

• one line is stored as-is, as a string (type [string]).

Therefore:

$val = python "D:\Dev\Python\Font Scripts\GetFontInfo.py" "D:\Fonts\00 Test\SharpSans-Bold.otf"

by itself is sufficient to capture the stdout output lines from your python call as an array - assuming there are two or more lines.

If you want to ensure that $val is always an array - even if there's only one output line, you have two options:

• Either: Use @(...), the array-subexpression operator:

$val = @(python "D:\Dev\Python\Font Scripts\GetFontInfo.py" "D:\Fonts\00 Test\SharpSans-Bold.otf")

• Or: Use an [array] type constraint (equivalent to [object[]]):

[array] $val = python "D:\Dev\Python\Font Scripts\GetFontInfo.py" "D:\Fonts\00 Test\SharpSans-Bold.otf"

Note:

• There are subtle differences between the two approaches above - see this answer for details.

• When PowerShell captures or redirects output from external programs, decoding into .NET strings based on the character encoding stored in [Console]::OutputEncoding is invariably involved - see this answer.

• To verify that $val is indeed an array, run $val.GetType().FullName.

• To print each array element on it own line, do not use Write-Host, simply submit $val on its own (which is equivalent to using Write-Output $val, though the latter's explicit use is rarely needed - see this answer for background information.

You can print the values line by line and split the output by newline as instructed here:

$arr = $val.Split([Environment]::NewLine)