The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Scripting’ Category

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PyGotham keynote: The Other Async (Threads + Async = ❤️)

Posted by jpluimers on 2019/09/18

Interesting talk:

Published on Oct 8, 2017

Screencast of my keynote presentation at PyGotham 2017, New York City. October 7, 2017. In this live-coded talk, I build a queue object that spans the world of threads and asyncio with a single unified API.

Via [WayBack] The Other Async (Threads + Async = ❤️) – screencast of David Beazley’s keynote at PyGotham 2017 – ThisIsWhyICode – Google+

–jeroen

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Posted in Development, Python, Scripting, Software Development | Leave a Comment »

GitHub – slikts/js-equality-game: The Worst Minesweeper 💣 Ever

Posted by jpluimers on 2019/09/10

[WayBack] GitHub – slikts/js-equality-game: The Worst Minesweeper 💣 Ever:

It’s in response to claims like this one by the well-known author getify:

However, implicit coercion is a mechanism that can be learned, and moreover should be learned by anyone wishing to take JavaScript programming seriously. Not only is it not confusing once you learn the rules, it can actually make your programs better! The effort is well worth it.

You can play it on [WayBack] JavaScript Equality Table Game: Find out how well you know (or don’t know) the JavaScript == operator rules

It reminds me of the hilarious video on Wat – Destroy All Software Lightning Talk : Gary Bernhardt : Free Download, Borrow, and Streaming : Internet Archive 

Based on:

Via:

–jeroen

Posted in Development, JavaScript/ECMAScript, Scripting, Software Development | Leave a Comment »

What do the three arrow (“>>>”) signs mean in python?

Posted by jpluimers on 2019/09/10

When starting to work with Python, a lot of examples contain the >>> characters on the first line often followed by ... characters on continuing lines.

They are about two things:

  1. interactive Python sessions
  2. doctest

The answers in [WayBack] What do the three arrow (“>>>”) signs mean in python? give insight in the various Python versions and how they prompt.

References from them:

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

Every time I try, I’m reminded of: You Don’ t Know JavaScript

Posted by jpluimers on 2019/09/05

I forgot how I originally bumped into the book series, but every time I try to program in JavaScript I’m reminded of them: You Don’ t Know JavaScript.

Originally a KickStarter project, they are now on GitHub and there is a Twitter account irregularly posting about them:

Titles

–jeroen

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Posted in Development, JavaScript/ECMAScript, Scripting, Software Development | Leave a Comment »

Python “NameError: name ‘socket’ is not defined”

Posted by jpluimers on 2019/09/05

I bumped into this a while ago, but could not find back the code example showing it, so below is the SO question to solve it:

NameError: name 'socket' is not defined

[WayBack] How to refer to a standard library in a logging configuration file?

Related: [WayBack] [Tutor] Socket error in class

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

python multithreading wait till all threads finished

Posted by jpluimers on 2019/09/04

A great tip from [WayBack] python multithreading wait till all threads finished:

ou need to use join method of Thread object in the end of the script.

t1 = Thread(target=call_script, args=(scriptA + argumentsA))
t2 = Thread(target=call_script, args=(scriptA + argumentsB))
t3 = Thread(target=call_script, args=(scriptA + argumentsC))

t1.start()
t2.start()
t3.start()

t1.join()
t2.join()
t3.join()

Thus the main thread will wait till t1, t2 and t3 finish execution.

I’ve used a similar construct that’s used by the multi-threading code I posted a few ways ago (on Passing multiple parameters to a Python method: the * tag) in the ThreadManager class below.

But first some of the other links that helped me getting that code as it is now:

Example:

class ThreadManager:
    def __init__(self):
        self.threads = []

    def append(self, *threads):
        for thread in threads:
            self.threads.append(thread)

    def runAllToCompletion(self):
        ## The loops are the easiest way to run one methods on all entries in a list; see https://stackoverflow.com/questions/2682012/how-to-call-same-method-for-a-list-of-objects
        # First ensure everything runs in parallel:
        for thread in self.threads:
            thread.start()
        # Then wait until all monitoring work has finished:
        for thread in self.threads:
            thread.join()
        # here all threads have finished

def main():
    ## ...
    threadManager.append(
        UrlMonitorThread(monitor, "http://%s" % targetHost),
        SmtpMonitorThread(monitor, targetHost, 25),
        SmtpMonitorThread(monitor, targetHost, 587),
        SshMonitorThread(monitor, targetHost, 22),
        SshMonitorThread(monitor, targetHost, 10022),
        SshMonitorThread(monitor, targetHost, 20022))

    threadManager.runAllToCompletion()

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

how to filter name/value pairs under a registry key by name and value in PowerShell?

Posted by jpluimers on 2019/09/03

A very concise way for [WayBack] how to filter name/value pairs under a registry key by name and value in PowerShell?:

$path = 'hkcu:\Software\Microsoft\Windows\CurrentVersion\Extensions'
(Get-ItemProperty $path).PSObject.Properties |
  Where-Object { $_.Name -match '^xls' ` -or $_.Value -match 'msaccess.exe$' } |
  Select-Object Name, Value

Thanks montonero for getting me on that path and pointing me to the hidden PSObject property which by itself has Properties, and making me find these links with background information:

More in-depth information:

  • [WayBack] Get-Member (Microsoft.PowerShell.Utility)
    • The Get-Member cmdlet gets the members, the properties and methods, of objects. To specify the object, use the InputObject parameter or pipe an object to Get-Member. To get information about static members, the members of the class, not of the instance, use the Static parameter. To get only certain types of members, such as NoteProperties, use the MemberType parameter.
    • -Force

      Adds the intrinsic members (PSBase, PSAdapted, PSObject, PSTypeNames) and the compiler-generated get_ and set_ methods to the display. By default, Get-Member gets these properties in all views other than Base and Adapted, but it does not display them.

      The following list describes the properties that are added when you use the Force parameter:

      • PSBase: The original properties of the .NET Framework object without extension or adaptation. These are the properties defined for the object class and listed in MSDN.
      • PSAdapted. The properties and methods defined in the Windows PowerShell extended type system.
      • PSExtended. The properties and methods that were added in the Types.ps1xml files or by using the Add-Member cmdlet.
      • PSObject. The adapter that converts the base object to a Windows PowerShell PSObject object.
      • PSTypeNames. A list of object types that describe the object, in order of specificity. When formatting the object, Windows PowerShell searches for the types in the Format.ps1xml files in the Windows PowerShell installation directory ($pshome). It uses the formatting definition for the first type that it finds.
  • [WayBack] PSObject Class (System.Management.Automation)
    • Wraps an object providing alternate views of the available members and ways to extend them. Members can be methods, properties, parameterized properties, etc.
  • [WayBack] PSObject.Properties Property (System.Management.Automation)
    • Gets the Property collection, or the members that are actually properties.
      Is of type PSMemberInfoCollection<PSPropertyInfo>
  • [WayBack] PSMemberInfoCollection<T> Class
    • Serves as the collection of members in an PSObject or MemberSet
  • [WayBack] PSPropertyInfo Class (System.Management.Automation)
    • Serves as a base class for all members that behave like properties.
  • [WayBack] Difference between PSObject, Hashtable and PSCustomObject
  • [WayBack] Combining Objects Efficiently – Use a Hash Table to Index a Collection of Objects
    • With objects objects everywhere it may not seem apparent, but hash tables are still needed.  When the PowerShell mind sets to work it can be very easy to use where and selects everywhere to get you…
  • [Archive.is] Custom objects default display in PowerShell 3.0
  • [WayBack] Using PSObject to store data in PowerShell | 9to5IT
    • PowerShell’s PSObject is a powerful tool which is used to store, retrieve, sort and export data. Here is how to use PSObject to store data in PowerShell.

–jeroen

Posted in CommandLine, Development, PowerShell, PowerShell, Scripting, Software Development | Leave a Comment »

Python: variables in the class scope are class, not instance

Posted by jpluimers on 2019/09/03

A very subtle thing that keeps biting me as my background is from languages where by default, identifiers on the class scope are instance level, not class level:

In Python, variables on class level are class variables.

If you need instance variables, initialise them in your constructor with a self.variable = value.

The example in the Python 3 docs [WayBack] Classes – A First Look at Classes – Class and Instance Variables is the same as in the Python 2 docs [WayBack] Classes – A First Look at Classes – Class and Instance Variables:

Generally speaking, instance variables are for data unique to each instance and class variables are for attributes and methods shared by all instances of the class:

class Dog:

    kind = 'canine'         # class variable shared by all instances

    def __init__(self, name):
        self.name = name    # instance variable unique to each instance

>>> d = Dog('Fido')
>>> e = Dog('Buddy')
>>> d.kind                  # shared by all dogs
'canine'
>>> e.kind                  # shared by all dogs
'canine'
>>> d.name                  # unique to d
'Fido'
>>> e.name                  # unique to e
'Buddy'

For people new at Python: the __init__ is a constructor; see these links for more explanation:

Of course, the __init__() method may have arguments for greater flexibility. In that case, arguments given to the class instantiation operator are passed on to __init__(). For example,

>>> class Complex:
...     def __init__(self, realpart, imagpart):
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex(3.0, -4.5)
>>> x.r, x.i
(3.0, -4.5)

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

Exploring Line Lengths in Python Packages

Posted by jpluimers on 2019/09/02

[Archive.is] Exploring Line Lengths in Python Packages is an interesting read.

It explores the relation between actual and “maximum” line lengths in Python in related to the prior 140 Twitter character limit.

via [Archive.is] Exploring Line Lengths in Python Packages – ThisIsWhyICode – Google+

–jeroen

Read the rest of this entry »

Posted in Development, Python, Scripting, Software Development, Static Code Analysis | Leave a Comment »

Passing multiple parameters to a Python method: the * tag

Posted by jpluimers on 2019/08/28

I had to pass parameters to a method so they became a list:

    threadManager.append(
        UrlMonitorThread(monitor, "http://%s" % targetHost),
        SmtpMonitorThread(monitor, targetHost, 25),
        SmtpMonitorThread(monitor, targetHost, 587),
        SshMonitorThread(monitor, targetHost, 22))

This appeared much easier than I anticipated:

    def append(self, *threads):
        for thread in threads:
            self.threads.append(thread)

It uses the * tag which is explained here:

–jeroen

Posted in Development, Python, Scripting, Software Development | Leave a Comment »

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