Archive for the ‘Development’ Category
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 »
Posted by jpluimers on 2019/09/04
“Functional programmer: (noun) One who names variables ‘x’, names functions ‘f’, and names code patterns ‘zygohistomorphic prepromorphism.'” — James Iry
–jeroen
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Posted in Development, Fun, Functional Programming, Quotes, Software Development, T-Shirt quotes | Leave a Comment »
Posted by jpluimers on 2019/09/03
Link archival: [WayBack] How to Install Node.js and NPM on a Mac:
In this article, I’ll take you through the process of installing Node.js and NPM on a Mac using Homebrew.
TL;DR
- Ensure you have installed
homebrew.
- Run
brew install node.
–jeroen
Posted in Apple, Development, Mac OS X / OS X / MacOS, Power User, Software Development | Leave a Comment »
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 »
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 »
Posted by jpluimers on 2019/09/02
Being a back-end and library person by heart, I am always late in the web-UI game, so this is on my list of things to try: CSS flex-box layout – Wikipedia.
I saw it being used by [WayBack] markdownlint demo: Demo for markdownlint, a Node.js style checker and lint tool for Markdown/CommonMark files.
Some links that should me help further:
–jeroen
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Posted in CSS, Development, HTML, HTML5, Software Development, Web Development | Leave a Comment »
Posted by jpluimers on 2019/08/29
ANWB can superimpose the lane availability indicators on their internap maps software.
Some links so I won’t forget:
–jeroen
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Posted in Development, Google, GoogleMaps, Power User, Software Development, Web Development | Leave a Comment »
Posted by jpluimers on 2019/08/29
via [WayBack] Writing solid code the NASA way. – Lars Fosdal – Google+, I bumped into [WayBack] How To Code Like The Top Programmers At NASA — 10 Critical Rules:
Do you know how top programmers write mission-critical code at NASA? To make such code clearer, safer, and easier to understand, NASA’s Jet Propulsion Laboratory has laid 10 rules for developing software.
The rules:
- Restrict all code to very simple control flow constructs – do not use goto statements, setjmp or longjmp constructs, and direct or indirect recursion.
- All loops must have a fixed upper-bound. It must be trivially possible for a checking tool to prove statically that a preset upper-bound on the number of iterations of a loop cannot be exceeded. If the loop-bound cannot be proven statically, the rule is considered violated.
- Do not use dynamic memory allocation after initialization.
- No function should be longer than what can be printed on a single sheet of paper in a standard reference format with one line per statement and one line per declaration. Typically, this means no more than about 60 lines of code per function.
- The assertion density of the code should average to a minimum of two assertions per function. Assertions are used to check for anomalous conditions that should never happen in real-life executions. Assertions must always be side-effect free and should be defined as Boolean tests. When an assertion fails, an explicit recovery action must be taken, e.g., by returning an error condition to the caller of the function that executes the failing assertion. Any assertion for which a static checking tool can prove that it can never fail or never hold violates this rule (I.e., it is not possible to satisfy the rule by adding unhelpful “assert(true)” statements).
- Data objects must be declared at the smallest possible level of scope.
- The return value of non-void functions must be checked by each calling function, and the validity of parameters must be checked inside each function.
- The use of the preprocessor must be limited to the inclusion of header files and simple macro definitions. Token pasting, variable argument lists (ellipses), and recursive macro calls are not allowed. All macros must expand into complete syntactic units. The use of conditional compilation directives is often also dubious, but cannot always be avoided. This means that there should rarely be justification for more than one or two conditional compilation directives even in large software development efforts, beyond the standard boilerplate that avoids multiple inclusion of the same header file. Each such use should be flagged by a tool-based checker and justified in the code.
- The use of pointers should be restricted. Specifically, no more than one level of dereferencing is allowed. Pointer dereference operations may not be hidden in macro definitions or inside typedef declarations. Function pointers are not permitted.
- All code must be compiled, from the first day of development, with all compiler warnings enabled at the compiler’s most pedantic setting. All code must compile with these setting without any warnings. All code must be checked daily with at least one, but preferably more than one, state-of-the-art static source code analyzer and should pass the analyses with zero warnings.
–jeroen
PS: twitter comment
“All code must compile with these settings without any warnings” – I absolutely agree with this. It really annoys me to find code which people have shipped which generates warnings. They’re there for a reason and should be fixed! 👍
Posted in Agile, Code Quality, Conference Topics, Conferences, Development, Event, Software Development | Leave a Comment »
The Wiert Corner - irregular stream of stuff 