PyCon 2011: IronPython Command Line

WRITING COMMAND-LINE TOOLS WITH IRONPYTHON AND VISUAL STUDIO Noah Gift Including PowerShell, and F#

Talk Objectives ¤  Freak you out a bit. ¤  Teach you something you didn’t know. (Not covered in any book). ¤  Be controversial. ¤  Entertain you.

Monty Hall Problem ¤  You are invited to a game show. ¤  Game show host shows you three doors. ¤  Behind two doors there is a goat, and behind one door is a $50,000 dollar sports car.

Monty Hall Problem ¤  You choose a door. ¤  Instead of opening your door. The game show host then opens up another door, to reveal a goat. ¤  Do you switch your choice?

Monty Hall Problem ¤  You always switch doors: 2/3 probability versus ½ probability. ¤  Bayes Rule shows us this: (Think Spam classification).

Monty Hall Takeaway ¤  This isn’t intuitive to most people ¤  The human brain’s intuition is often broken. ¤  What else is your brain wrong about?

Windows Is The Great Satan? ¤  Command-line is feeble ¤  People on twitter say it sucks ¤  Nothing COOL ever happens on Windows ¤  This isn’t “their” conference. ¤  What if your brain’s intuition is wrong about this too?

I Used To Hate Windows ¨  I Grew Up ¨  New Philosophy: Write Code in any language, in any environment. ¨  If it is innovative, I don’t care who made it. ¨  Sorry Stallman, we disagree.

What do most developers and admins think of when they hear Linux? ¨  Power ¨  The Shell ¨  Flexibility ¨  Command-tools ¨  Bash ¨  Man Pages ¨  SSH ¨  Awk/Sed

What Is The Unifying Theme Around This? ¨  String Output is King ¨  Tim O’Reilly in Unix ¨  Small Tools Power Tools, “A new ¨  Flexibility user by stringing together simple ¨  Geek Power. pipelines….”

The Hardest Part of Writing a *Nix Command-line tool in Python ¨  Remote Administration: ¨  Religious war in your Pyro vs SSH vs ??? company over using ¨  Dealing with *Nix tools optparse, getargs, that pass you back or argparse unstructured text.

Python/Unix Command-line Tools: The End Game ¨  Remote Object Invocation (Pyro, SSH, Fabric) ¨  Security (SSH, SSL) ¨  Automation ¨  Application API ¨  Event Management (Pyro) ¨  Transactions (Mercurial?)

How To Write A Classic IronPython CLI ¨  I needed to upgrade 100’s of thousands of lines of C# to .NET 4.0. ¨  I wrote a quick and dirty Command-line tool in IronPython.

Project Upgrader: Validate Version Step 1 def validate_vsver(slnfile): """Validates whether a .sln file has already been upgraded to VS 2010""" try: project_file = open(slnfile) for project_version_line in project_file.readlines(): if "Visual Studio 2010" in project_version_line: log.debug("Found VS 2010 project line: %s" % project_version_line) log.debug("Project file already upgraded....skipping: %s" % slnfile) return False return True finally: project_file.close()

Project Upgrader: Walk A Tree Step 2 def walk_tree(path, extension="sln", version_control_type=".svn", exclude_path=None): """Walks a tree, if there is a match to an extension, it returns a fullpath. Skips version_control_type directories, which by default is set to .svn """ for dirpath,dirname,filename in os.walk(path): #The walk should skip version control directories for dir in dirname:

Project Upgrader: Convert Project Step 3 def convert_project(filename): """Converts a project to VS2010 using deven via .NET Process Class""" p = Process() p.StartInfo.UseShellExecute = False p.StartInfo.RedirectStandardOutput = True p.StartInfo.RedirectStandardError = True p.StartInfo.FileName = """C:Program Files (x86)Microsoft Visual Studio 10.0Common7IDEdevenv.exe""" print "Stdout: %s| Stderr: %s" % (stdout, stderr) p.WaitForExit() return p.ExitCode

Project Upgrader: Convert Tree Step 4 def convert_tree(path, exclude_path): """Recursively modifies a tree of sln files, if they haven't been upgraded to VS 2010""" for file in walk_tree(path, exclude_path=exclude_path): if not validate_vsver(file): #we should pass upgrading if validate_vsver returns False continue exit_code = convert_project(file) log.info("%s, %s" % (exit_code, file))

Project Upgrader: Run method Step 4 def run(self): args, parser = self.options() if args.path: exclude = None if args.exclude: exclude = args.exclude log.info("Exclude set: %s" % exclude) log.info("%s Running VS2010 upgrade on tree: %s | excluding dirs named: %s" % (time.ctime(), args.path, exclude)) convert_tree(args.path, exclude_path=exclude) else: parser.print_help()

Python is like Kudzu ¤  Itsstrength is that it can embed itself into any project, any operating system. ¤  Not always the best tool, but often good enough.

Who Is The Target Audience For Command-line Tools? ¤  Systems Administrators ¤  Power Users ¤  Developers ¤  Systems Integrators/OEM ¤  Young Geeky Stallman

What Does It Really Mean To Write A Command-line tool on Linux ¤  You have an executable that runs in the context of, most likely, Bash. ¤  You output a string, which you can then pipeline into our Unix tools, sed, awk, grep. ¤  If your nice you create –help

What Does It Really Mean To Write A Command-line tool on Modern Windows ¤  Itis going to run inside of PowerShell. PowerShell is your bash. ¤  You have a unified interface to .NET and every possible high level automation API you can think of. ¤  PowerShell tools expect OBJECTS not strings.

PowerShell is Secure By Default ¤  Default File Association is Notepad or ISE. ¤  Remoting is disabled. ¤  No execution of scripts. ¤  Script Signing

Learning To Properly Write IronPython Command-Line Tools: “A two minute affair” ¤  Actually no, not even close. ¤  Forget “most” of what you know from linux. ¤  PowerShell changes everything.

PowerShell Object Passing Changes How Shells Work ¤  Fundamental change to understand ¤  You need to understand this to write command-line tools on Windows ¤  Game changer

We’re not in a flyover state anymore ¤  String output is lame! ¤  PowerShell wants objects ¤  What to do…what to do…

Fight the ecosystem and you will die ¤  Command-line tools should run in PowerShell not cmd.exe. ¤  The bash/linux CPython way, won’t cut it here. ¤  You must think the way .NET thinks. ¤  Everything takes and returns an Object.

PowerShell Endgame: We did EVERYTHING for you. ¤  Encrypted, paranoid secure, transactional, asynchronous remoting of serialized objects ¤  High level automation API to everything. ¤  Ignore at your own peril.

Writing a PowerShell Module In IronPython: The “real” way to write Command-line tools? ¨  Create a New Visual Studio Project ¨  Thinks Objects ¨  Use PowerShell SDK ¨  Write a Binary Module

Installing the PowerShell SDK ¤  Download the SDK ¤  Add a reference to the DLL in your Visual Studio Project ¤ C:ProgramFiles (x86)Reference AssembliesMicrosoftWindowsPowerShell v1.0System.Management.Automation

Finding and Loading PowerShell Modules ¨  Get-Module –all ¨  When you create a .dll in IronPython, could then simply integrate it into the PowerShell workflow.

What is a Binary Module? ¤  A .NET assembly compiled against PowerShell libraries. ¨  For IronPython folks, this is one way to integrate into PowerShell ¨  In a lot of documentation it will refer to C# code. ¨  You can also write a PowerShell, non-compiled, module.

Creating a Binary Module For Powershell in IronPython ¤  http://stackoverflow.com/questions/2094694/launch- powershell-under-net-4 ¤  You need to tweak some registry settings to support .NET 4.0 in PowerShell.

Creating a Binary Module For Powershell in IronPython: Continued ¤  Should follow C# example code for best implementation advice. ¤  Note, Argparse, Optparse, etc, aren’t used. They don’t make sense. ¤  These are objects being passed into other cmdlets, and methods are being called on those objects.

IronPython PowerShell Module Hello World Visual Studio import clr Project: clr.AddReference('System.Management.Automation') print 'Hello World' Step 1

IronPython PowerShell Module Hello World Visual Studio ¨  Build the project to create a .dll Project: ¨  In PowerShell Import Module Step 2 ¨  Import-Module MyModule.dll ¨  You can know interact with it from inside of .Net. Is this a commandline tool???

Setting Up A PowerShell Profile For IronPython ¨  Just like in Bash or ZSH, aliases are your friend. ¨  Edit your $profile with the ISE, and add interactive IronPython to it.

Creating Standalone IronPython executables ¨  Make sure you can pass objects in and out of them. ¨  Use the IronPython on codeplex: Pyc-Python Command-line compiler

F#: The Elephant in the Room ¤  Type inference ¤  Immutable data structures ¤  Run as script or compiled ¤  Tail recursion ¤  Fully integrated with Visual Studio ¤  Sexier then Python?

F# and Python: A Sexy Beast ¤  Mixing .dll files written in F# into IronPython modules, loaded into Powershell. ¤  Calling IronPython/CPython from inside of F# ¤  “A statically typed Python…” (Note, this will come up..just preparing you…)

Credit Some Excellent Books That Reference PowerShell ¤  PowerShell in Action, Manning (The Bible) ¤  PowerShell Cookbook, O’Reilly ¤  IronPython in Action, Manning

Conclusion ¤  PowerShell isn’t a competing language, it IS THE ECOSYSTEM. ¤  Windows Systems Admins are using PowerShell for everything ¤  Get your head wrapped around object based pipelines. ¤  Why doesn’t Linux have this?

Questions? Code: https://bitbucket.org/noahgift/pycon2011- ironpython-cli

PyCon 2011: IronPython Command Line

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PyCon 2011: IronPython Command Line