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 ‘Software Development’ Category

Happy 30th birthday Mac!

Posted by jpluimers on 2014/01/24

Being away from a computer sometimes means you forget about events.

So before I forget: happy 30th birthday Mac!

For me, real programming started 31 years ago on an Apple II at high school, soon followed by a II+ and a //e. At first, I was programming in both Integer Basic and AppleSoft Basic, then with Apple Pascal (which was based on UCSD Pascal, but way too slow), and finally with Turbo Pascal 1.0 (after they installed a Microsoft Z-80 softcard in a few of the machines which allowed it to run CP/M).

Back then me, nor my parents could afford a computer like a Mac, but I was lucky enough to keep on people at the “close by” (30 minutes by bicycle) University to use one and program in hyper card and various Pascal dialects (and later Delphi).

Now I own a few Macs (most more portable than the //c) bought a //e and //c last summer and collecting some extension cards to make life easier.

Just look at the B&N magazine rack how popular the Apple stuff is today:

image

So again: happy 30th birthday Mac!

Without you, I wouldn’t be a software developer.

–jeroen

via: Apple bracht eerste Mac-computer 30 jaar geleden uit – Computer – Nieuws – Tweakers.

Posted in //e, Apple, Apple Pascal, Delphi, Development, Mac, Mac OS X / OS X / MacOS, Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, Mac OS X 10.7 Lion, MacBook, MacBook Retina, MacBook-Air, MacBook-Pro, Object Pascal, OS X 10.8 Mountain Lion, OS X 10.9 Mavericks, Pascal, Power User, Software Development, Think Pascal, Turbo Pascal, UCSD Pascal | 1 Comment »

Generate HTML Tables Clean and Fast

Posted by jpluimers on 2014/01/23

I wish I had found about Generate HTML Tables Clean and Fast years ago.

Every once in a while I want to generate the source code for an HTML table with some content easily.

I’ve found no tool doing this in an easy manner and starts in a split second.

But the web page Generate HTML Tables Clean and Fast does.

Correction: did. It is now off-line, but the Blended Technologies » Blog Archive  blog posts about it are still online: Introducing TableGen – The HTML Table Generator and Tablegen Goes Open Source, as is the WayBack machine archive for it.

So I installed Python on my openSUSE server according to Embedding Python In Apache2 With mod_python (… OpenSUSE) | HowtoForge, (could as well have configured in httpd.conf in stead of python.conf: no difference between installing mod_python via httpd.conf and conf.d in apache) then installed the TableGen source there.

(Note: more python.conf examples)

That would still have Python generate a 404 error (uncool: a python generated 404 error does not leave a log of the cause anywhere), not because the index.py was absent, but because it was written in old style “print” statements, not using the new style def index(req); way (thanks Senthil Kumaran, and AJ. for your answer).

So I did some research (this was my first encounter with Python) at for instance Paul Osman : Introduction to mod_python, then rewrote the print parts of the script into string concatenations, then return the full HTML.

(Note: if there is a print "Content-Type: text/html" (for instance demonstrated in Hello World | Web Python), you can omit it, or set the req.content_type like req.content_type = 'text/html' which usually is determined automatically by Python).

That caused quite a few IndentationError: expected an indented block quote errors: python is indentation sensitive (I hadn’t used a language depending on that for ages), and gives a confusing error when you have a colon (:) followed by an unindented docstringPython: I’m getting an ‘indented block’ error on the last 3 quotes (“””).

Then it still didn’t completely work: the form parameters would not be obtained correctly, so I read further, found 3.1 A Quick Start with the Publisher Handler and started to fix that too. That took way too long, so I found out that “mod_python” is not very much maintained any more and “mod_wsgi” is the way to go.

So I disabled the “python” module in YaST2, removed “/etc/apache2/conf.d/python.conf”, then installed the “apache2-mod_wsgi” software package in YaST2, then added the “wsgi” module to HTTP Server Configuration list of Server Modules (it automatically gets enabled) and saved the configuration.

These steps modified the APACHE_MODULES in /etc/sysconfig/apache2, restarted apache with “rcapache2 restart”. You can verify with “httpd2 -M” which modules are loaded. The list should exclude “python_module (shared)” and includes “wsgi_module (shared)”.

Most of this is described in has anyone gotten mod_wsgi working.

Python is whitespace sensitive, but you can have multiple statements on one line. That’s why Python allows semicolons after each statement.

Read Setting up Python with WSGI on Apache for a directory – Stack Overflow.

Read PyCon Conference Slides – Sydney 2010 – Python WSGI adapter module for Apache.

Read Graham Dumpleton: Why are you using embedded mode of mod_wsgi?.

Read Serving Python scripts with Apache mod_wsgi, part I | Leave No Bit Unturned.

Read Parsing the Request – Get | Web Python.

Watch WSGI Tutorial. It explains a lot, including Accessing POST Data from WSGI.

Error “Attempt to invoke directory as WSGI application” -> you cannot do that, there is no way to map a directory to an “index.py” in that directory.

For importing .py files from the same directory as your main .py file:

    import os
    import sys

    directory = os.path.dirname(__file__)
    sys.path.insert(0, directory)

    from webutils import *

Start using The Web framework for perfectionists with deadlines | Django.

A few really cool things about this page:

  • It is a web page, so easy to reach
  • It starts fast
  • You can increase the column/row count without loosing the entered data
    (as it stores the contents as a URL)
  • It can generate a thead for you
    (but not a tfoot)

Generating something like this was a breeze: Read the rest of this entry »

Posted in *nix, Apache2, Development, HTML, Linux, openSuSE, Power User, Software Development, SuSE Linux, Tumbleweed, Web Development | Leave a Comment »

Faking num lock, caps lock and scroll lock leds – About My Code

Posted by jpluimers on 2014/01/21

I remember doing this in DOS ages ago (in the Turbo Pascal 5 era) for exactly the same reason: flash the keyboard LEDs to indicate some event was happening, but I’ve yet to find back the source code.

Here is how to do it in Windows using either C# or C: Faking num lock, caps lock and scroll lock leds – About My Code.

–jeroen

via: c# – Way to turn on keyboard’s caps-lock light without actually turning on caps-lock? – Stack Overflow.

Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, C++, Development, Pascal, Software Development, Turbo Pascal | Leave a Comment »

Word 2007/2010/2013: Enabling the Word Developer Tab on the ribbon (via: Andrew Coates ::: MSFT – Site Home – MSDN Blogs)

Posted by jpluimers on 2014/01/16

This is one of the things I tend to forget, as you do it once per machine, and the place to do it is not logical to me.

I mainly use it to quickly record a Macro (boy, I wish Office had a TemporaryMacro feature like Visual Studio had. Alas no more: Macro Recording/Playback has been removed in Visual Studio 2012).

The logical place for me would be to have a context-menu on the ribbon where you can enable the Developer tab.

Anyway, this is how to enable the Developer tab in Word 2007/2010/2013: Read the rest of this entry »

Posted in Development, Office, Office 2007, Office 2010, Office 2013, Power User, Software Development, Visual Studio 11, Visual Studio 2002, Visual Studio 2003, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio and tools, Word | Leave a Comment »

.NET/C#: you cannot do string? because Nullable is for value type, and string is a reference type

Posted by jpluimers on 2014/01/15

At clients, I see quite a few people being confused by this compiler error message:

Error 1 The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable'

One of the reasons about the confusion is that a string variable behaves like a value type, but in fact is a reference type because their values can consume a huge amount of memory (thanks User codekaizen).

A few interesting questions on that on StackOverflow:

Anyway, back to the error message above.

Lots of people are confused by it, just see a few questions on StackOverflow: Read the rest of this entry »

Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Jon Skeet, Software Development | Leave a Comment »

Pre-build trick does not work to circumvent [BRCC32 Error] xxx.vrc(1): error creating xxx.res (via: Embarcadero Discussion Forums & StackOverflow)

Posted by jpluimers on 2014/01/10

Ever since around Delphi 2007, it started to use temporary .VRC files to re-build the project .RES file.

It confuses people, and with reason as the only public information about it on the dockwiki seems to be in the Version Info page (though there is more on the other embarcadero sites).

The reason is that parts of the .RES file are no more leading in the process of getting them from your project options to the final binary (EXE/DLL/BPL/…) of your project.

Delphi XE3 for instance can have these resource structures in the .VRC file:

Except for type 24, Delphi XE2 seems to have the same kinds of resource types.

All in all, most if not all of the .RES files are being auto-generated for at least a couple of years now so there is less and less need to put it under version control.

The problem is that if for one reason or the other, your project .RES file becomes readonly, and you get errors like mentioned in Why does a projects res file need to ….

[BRCC32 Error] xxx.vrc(1): error creating xxx.res

.RES in VCS or not?

Read the rest of this entry »

Posted in Conference Topics, Conferences, Delphi, Delphi XE, Delphi XE2, Delphi XE3, Delphi XE4, Delphi XE5, Development, Event, QC, Resource Files and Scripts (.res/.rc), Software Development | Leave a Comment »

When two types are not the same: Assembly Load Contexts Subtleties (via: All Your Base Are Belong To Us)

Posted by jpluimers on 2014/01/09

Reading c# – Type.IsSubclassOf does not behave as expected – Stack Overflow, I found this very interesting link via Assembly Load Contexts Subtleties at Sasha Goldshtein’s blog (I love the name of the blog: All Your Base Are Belong To Us).

He explains the reasons for the error message

System.InvalidCastException: Unable to cast object of type ‘Plugin.MyPlugin’ to type ‘Plugin.MyPlugin’.

Actually his blog entry is an abstract of a 200+ page thesis on  that is also recommended reading: Flexible Dynamic Linkin for .NET (by Anders Aaltonen, Alex Buckley and Susan Eisenbach).

–jeroen

via:

Posted in .NET, .NET 3.5, .NET 4.0, .NET 4.5, .NET CF, C#, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »

.NET/Visual Studio: The ContextSwitchDeadlock doesn’t necessarily mean your code has an issue.

Posted by jpluimers on 2014/01/07

Thanks Pedro! (emphasis below is mine)

The ContextSwitchDeadlock doesn’t necessarily mean your code has an issue, just that there is a potential.

If you go to Debug > Exceptions in the menu and expand the “Managed Debugging Assistants”, you will find ContextSwitchDeadlock is enabled.

If you disable this, VS will no longer warn you when items are taking a long time to process.

In some cases you may validly have a long-running operation.

It’s also helpful if you are debugging and have stopped on a line while this is processing – you don’t want it to complain before you’ve had a chance to dig into an issue.

–jeroen

via: c# – Visual Studio: ContextSwitchDeadlock – Stack Overflow.

Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, Development, Software Development, Visual Studio 11, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio and tools | Leave a Comment »

Delphi SOAP: some reminders to Self

Posted by jpluimers on 2014/01/04

Hadn’t been doing SOAP in Delphi for a while, and needed to send some Delphi data structures over the write where both Client and Server were going to be Delphi.

These links helped me:

If both client and server are Delphi, you can share the interface units and registration.

Note: since native Delphi SOAP support uses old-skool RTTI, so any property you want to go over the wire needs to be published, not public.

If you want to go beyond that, or use other protocols than SOAP, use libraries for Delphi like RemObjects SDK.

–jeroen

Posted in Conference Topics, Conferences, Delphi, Delphi XE3, Delphi XE4, Delphi XE5, Development, Event, Software Development | Leave a Comment »

Niklaus Wirth’s “Good Ideas, Through the Looking Glass” (via: MetaFilter)

Posted by jpluimers on 2014/01/02

I forgot who pointed me at this, but recently I came across a reference to the Good Ideas, Through the Looking Glass paper by Niklaus Wirth (by many known as the “father” of Pascal, though he has done a lot more – for instance the WSN – , still is involved with the ETH in Zürich, and turns 80 on February 15h).

Back when it appeared in the 2005/2006 timeframe I missed it, and I’m glad to have bumped into just for the historic perspective he offers. I can understand some will disagree with parts of his conclusions and observations, that’s why I like that MetaFilter has a nice page with discussion about it and a link to the PDF version of the paper.

I also like that Niklaus kept active in the field of computer science for so long, similar to Donald Knuth. There is a lot to having a great historic perspective to things.

–jeroen

via: Good Ideas, Through the Looking Glass | MetaFilter.

Posted in Delphi, Development, History, Pascal, Software Development | 3 Comments »