User:CBM-c-/VS-Py Rosetta Stone

VS-Python Rosetta Stone

Transitioning from Vectorscript Pascal to Vectorscript Python has its challenges, here a Rosetta Stone to help you out with the task.

Note

as of today the wiki doesn't accept external links, which are thus not clickable.

Set up Python (Mac)

As of this writing, Vectorworks requires Python 3.x. MacOS X before 10.15 ships with Python 2.x. VW delivers the right Python, so you don't need to do anything special if there are no external, vw-unrelated reasons to do so. Should you wish to modify the Python installed on your machine you can proceed as follows, but this won't modify the shipped VW Python. For example, you might want to do some terminal tutorials using the right version.

• launch the Terminal
• type: python3 --version; if there is an error, you should install Python 3 and configure it.
• follow the instructions on installpython3.com/mac/.

This document is very complete and leads you step by step through the rather cryptical configurations. During this process you will install XCode and Homebrew through the terminal.

Warning

For some reason the XCode wouldn't install on my MacOS X.14. After various hours of fumbling, I gave up and went straight to the official Python 3 installer, which is available at www.python.org/downloads/release/python-391/

After that I proceeded with the configurations as described in installpython3.com/mac/ and all seems well enough.

Set up an editor

I tried using Aptana but couldn't configure it. Then I found at Computerworks excellent instructions by Oliver Daus for Visual Studio Code: (German) www.vectorworksforum.eu/topic/14087-entwicklungsumgebung-für-vectorworks-python-plug-ins/

• Download Visual Studio Code from code.visualstudio.com and install it
• Install the Python extension: launch Visual Studio Code, click on Extensions (shift +cmd + X), click on the search field, enter ms-python, click on install Python.

VS - Py

Description	Vectorscript	Python
Indenting	irrelevant	Fatal: error unindent does not match any outer indentation level: you used both spaces and tabs to indent your code. This occurs frequently while copy-pasting across sources. error unexpected indent: you added an extra indent. This is common in Pascal, just to visually organise the code.
Statement ending	Semicolon always needed: AlrtDialog('test 1') AlrtDialog('test 2') { error } AlrtDialog('test 1'); AlrtDialog('test 2'); { OK } AlrtDialog('test 1') AlrtDialog('test 2') { error }	Semicolon needed only for multiple statements on one line: vs.AlrtDialog('test 1') vs.AlrtDialog('test 2') # OK vs.AlrtDialog('test 1'); vs.AlrtDialog('test 2') # OK vs.AlrtDialog('test 1') vs.AlrtDialog('test 2') # error Error Message: SyntaxError: invalid syntax
Case sensitivity	Not case sensitive: AlrtDialog('test'); { OK } alrtDialog('test'); { OK } alrtdialog('test'); { OK } ALRTDIALOG('test'); { OK }	Case sensitive: vs.AlrtDialog('test') # OK vs.alrtDialog('test') # error vs.alrtdialog('test') # error vs.ALRTDIALOG('test') # error Error Message: AttributeError: 'module' object has no attribute 'vs.ALRTDIALOG'
Empty brakes for functions don't forget in python the empty brakets for routines without parameters, this rises errors that are so tricky to find.	Can be without brakets FSActLayer; { no parameters: brakets not needed } MySubroutine;	Can't be without brakets vs.FSActLayer() MySubroutine() Error Message: - none! be careful! -
Empty handles do pay attention also to the variable scope (see below).	h <> NIL	h != None h != vs.Handle() # not inited instance of a handle, how cryptic
Variable scope perhaps the largest source of error for the vectorscripter transitioning to python	Global wins over local: Variables must be declared Subroutines "see" their own variables and those of any parent function/procedure where they are contained. { GLOBAL ACCESS } { parent of subroutine "Increment" } PROCEDURE Main; VAR { good praxis: label globals with "g" } gIndex, gNum : INTEGER; { subroutine } PROCEDURE Increment; BEGIN { gNum is not defined in this subroutine the parser climbs up parent containers until it finds a declaration for the var gNum. In this case it can be found in Main } gNum := gNum +1; SysBeep; END; BEGIN gNum := 10; { init } FOR gIndex := 1 TO 10 DO Increment; { increments the variable gNum } AlrtDialog(Concat(gNum)); { returns 20 } END; Run(Main);	Local wins over global: Variables must NOT be declared Subroutines create automatically a local instance of any used variable. # LOCAL ACCESS # subroutine def Increment(): # gNum is not defined in this subroutine # the parser creates a local instance of the var gNum! gNum +=1 vs.SysBeep gNum = 10 # init for gIndex in range(1, 10): Increment # increments the variable gNum # but only inside Increment! vs.AlrtDialog(str(gNum)) # returns 10! The global var didn't set # GLOBAL ACCESS: CORRECT # subroutine def Increment(): # gNum is not defined in this subroutine # tell the parser that you want to edit gNum global! global gNum gNum +=1 vs.SysBeep() gNum = 10 # init # please observe that the range is NOT 1, 10! for gIndex in range(0, 10): Increment() # increments the variable gNum # but only inside Increment! vs.AlrtDialog(str(gNum)) # returns 20 # GLOBAL ACCESS: WRONG # subroutine def Increment(): # gNum is not defined in this subroutine # tell the parser that you want to edit gNum global! global gNum gNum +=1 vs.SysBeep() # no init! for gIndex in range(0, 10): Increment() # increments the variable gNum # but only inside Increment! vs.AlrtDialog(str(gNum)) # rises error Error Message: NameError: global name 'gNum' is not defined
FOR statements	Runs including last value: { runs 3 times! 1, 2 and 3 } FOR i := 1 TO 3 DO AlrtDialog(Concat(i));	Runs excluding last value: # runs 2 times! 1 and 2 for i in range(1, 3): vs.AlrtDialog(str(i))
Colors	Color Index: SetPenFore(h, RGBToColorIndex(65535, 0, 0)); PenFore(RGBToColorIndex(65535, 0, 0)); RGB: SetPenFore(h, 65535, 0, 0);	Color Index: vs.SetPenFore(h, vs.RGBToColorIndex(65535, 0, 0)) RGB in Tuple: vs.SetPenFore(h, (65535, 0, 0)) Hex in Tuple: vs.SetPenFore(h, (0xFFFF, 0, 0)) Warning: don't forget the brakets: vs.PenFore((65535, 0, 0)) correct vs.PenFore(65535, 0, 0) fails Error Message: - none! be careful! -
Concatenate text	Supports implicit conversion: Both Concat and Message support multiple variable types and convert them into string. t := Concat(10, ' fingers'); { OK } Message(10, ' fingers'); { OK } AlrtDialog(Concat(10, ' fingers')); { OK }	Doesn't support implicit conversion: For example an integer won't automatically be converted into string. Wrap it in vs.Concat or vs.Message, alternatively perform the needed conversion. t = 10 + ' fingers' # error t = vs.Concat(10, ' fingers') # OK vs.Message(10, ' fingers') # OK vs.AlrtDialog(str(10) + ' fingers') # OK vs.AlrtDialog(10 + ' fingers') # error Error Message: TypeError: unsupported operand type(s) for +: 'int' and 'str'
Encryption	Whatever .vs or .px file is linked through your includes, will be encrypted upon running the encrypt command. More infos about standard Vectorscript (Pascal) encryptions are here.	Create list of your included files in an xml file. For encryption in Python there are difficulties. Instructions from Vlado on the Techboard, search for "problems-encrypting-a-python-script" (at the moment we cannot add external links to the present wiki).
Python version		import sys ver = sys.version_info vs.Message(repr(ver))
"import"		import vs # do I need this?
Caching some caching prevents your script to reflect changes:		varPersistentPythonEngine = 412 { Boolean } In the SDK starting from VW 2014 we can read: When True the Python engine is the same for the execution of all scripts, this solves some issues with Py_Initialize and Py_Finalize. For example, when debugging externally python leaves threas that cause crash if Py_Initialize and Py_Finalize is used for each script call. So, this allows the engine to be preserved between calls, however Vectorworks will delete all custom modules and objects defined in the engine prior each execution.

Lists

Lists are powerful in Python, below some fascinating lists manipulations. They remind me of Applescript:

months = "Jan Feb Mar Apr May Jun Jul"
months = months.split() # no splitter defined and it will use the empty space --> ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul']
months[2] # --> 'Mar' note that the index is 0-based
months2 = "Jan, Feb, Mar, Apr, May, Jun, Jul"
months2.split(', ') # --> ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul'] use comma and empty space as splitter 
months.append('Jul') # --> ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul'] append adds an item to a list 
months.pop() #- -> 'Jul' pop fetches the last item of a list
', sunny '.join(months) # --> ', sunny Jan, sunny Feb, sunny Mar, sunny Apr, sunny May, sunny Jun, sunny Sep'
'-'.join(months[1:3]) # --> 'Feb-Mar'
del months[2] # --> ['Jan', 'Feb', 'Apr', 'May', 'Jun', 'Jul']
months = {1: 'Jan', 2: 'Feb', 3: 'Mar'} # --> {1: 'Jan', 2: 'Feb', 3: 'Mar'}

Errors

Python Error Messages:

BaseExceptions:

+-- SystemExit
+-- KeyboardInterrupt
+-- GeneratorExit
+-- Exception
     +-- StopIteration
     +-- ArithmeticError
     |    +-- FloatingPointError
     |    +-- OverflowError
     |    +-- ZeroDivisionError
     +-- AssertionError
     +-- AttributeError
     +-- BufferError
     +-- EOFError
     +-- ImportError
     +-- LookupError
     |    +-- IndexError
     |    +-- KeyError
     +-- MemoryError
     +-- NameError
     |    +-- UnboundLocalError
     +-- OSError
     |    +-- BlockingIOError
     |    +-- ChildProcessError
     |    +-- ConnectionError
     |    |    +-- BrokenPipeError
     |    |    +-- ConnectionAbortedError
     |    |    +-- ConnectionRefusedError
     |    |    +-- ConnectionResetError
     |    +-- FileExistsError
     |    +-- FileNotFoundError
     |    +-- InterruptedError
     |    +-- IsADirectoryError
     |    +-- NotADirectoryError
     |    +-- PermissionError
     |    +-- ProcessLookupError
     |    +-- TimeoutError
     +-- ReferenceError
     +-- RuntimeError
     |    +-- NotImplementedError
     +-- SyntaxError
     |    +-- IndentationError
     |         +-- TabError
     +-- SystemError
     +-- TypeError
     +-- ValueError
     |    +-- UnicodeError
     |         +-- UnicodeDecodeError
     |         +-- UnicodeEncodeError
     |         +-- UnicodeTranslateError
     +-- Warning
          +-- DeprecationWarning
          +-- PendingDeprecationWarning
          +-- RuntimeWarning
          +-- SyntaxWarning
          +-- UserWarning
          +-- FutureWarning
          +-- ImportWarning
          +-- UnicodeWarning
          +-- BytesWarning
          +-- ResourceWarning