M3PGS/2E0PGS blog

REPL maths 2

Thu, 03 Nov 2022 20:24:10 +0000

bc, power of zero, PSION programming and REPL

See part 1: Maths, notation, calculators and REPL programming

Modulo/remainders

bc

GNU BC: “modulo” % with scale other than 0

bc -l

scale
20
5 - (5/2) * 2
0
5 - (5/4) * 4
0
5%4
0

scale=0
5 - (5/2) * 2
1
5 - (5/4) * 4
1
5%4
1

Another GNU BC gotcha is the order of precedence aka order of operations is different to C. See comments here: https://www.gnu.org/software/bc/manual/html_node/bc_13.html

That is one reason to use parentheses in large equations to make it more readable and avoid the need to recall many different orders of precedence.

C#

C# Remainder operator % integer and floating point

I was doing some maths in C# for fun which turned out to be “Multinomial distribution” (TODO: more on this in another post) and as I was running multiple iterations with larger and larger numbers I recalled about a nice C# feature for making large literal numbers easier to read.

int i = 100000000;
int n = 100_000_000;

Also see: What do the underscores mean in a numeric literal in C#?

To the power of zero

BC

JavaScript

1**0
1
2**0
1
0**0
1

C#

Console.WriteLine(Math.Pow(0, 0));

Output

C++

printf("%f", pow(0, 0));

Output

1.000000

SQL (Microsoft)

select power(0, 0);

Output

LibreOffice Calc

=0^0

Output

Microsoft Excel

=0^0

Output

Number Error

PSION Series 3a Calc app

More below on the PSION in another heading. Note if you run the second before last statement in OPL you’ll get a runtime error not a compile/translate time error.

  1**0
= 1
  2**0
= 1
  0**0 "Invalid arguments"
  2^7 "Illegal character"

Casio fx-991ES PLUS

Much to my annoyance it only has a exponent button and not a dedicated power of caret button. This basically means it semi expects some equation inside parentheses and opens a parenthesis. The redeeming factor is that it implicitly closes the parentheses.

2^(7
1^(0
2^(0
0^(0

Output

128
1
1
Math ERROR

It wont however implicitly open a parenthesis:

2+2)*2

Output

Syntax ERROR

This model has LCD display glare too.

Casio fx-83MS

This calculator I prefer over my fx-991ES PLUS. It has zero display glare and richer text due to the non glossy simpler LCD. It also has the caret button of which I prefer as it doesn’t try to open parentheses unless I choose to. So input is more readable when written out verbatim unlike the fx-991ES PLUS unless I manually close the parentheses. The buttons are also a bit better quality.

2^7
1^0
2^0
0^0

Output

128
1
1
Math ERROR

PSION Series 3a PDA

Calc app

Psion 3a Series User Manual

Using “Menu” button you get access to various functions just a few examples:

sin(x)
cos(x)
tan(x)
log(x)

In the menu is the option for power of, which generates a place holder: (x)**2

Sadly no pow(x) function.

  (2)**7
= 128

It works without parentheses also:

  2**7
= 128

The “Sheet” app works with the 2**7 but not 2^7 much like the “Calc” app.

The functions work with a space after comma.

  max(22,5)
= 22
  max(22, 5)
= 22

OPL programming

Another great old WYSIWYG website: Steve Litchfield - OPL programming

Random interesting page about Python on Symbian: Steve Litchfield - Introduction to Python on Nokia/Symbian Series 60

PSION Series 3a - PSION Programming Reference (Dave Stafford)

PROC myprog:
	PRINT "case insensitive"
	print "yes"
	get
	print "semi colon";
	print "foo"
	print "bar"
	get
ENDP

Output

case insensitive
yes

Key press

semi colonfoo
bar

Key press terminates. Interesting how the semi colon behaves.

Maths

print max (1, 6)
print 2**7
get

Output

6
128

A list of more REPLs

Only ones not mentioned on the first post.

Arduino is C++

Wed, 16 Mar 2022 21:17:19 +0000

Is Arduino C++?

A friend asked the following questions which provoked some thought:

> Is Arduino its own language?
> Is Arduino based on Processing, Java, C++ or C?
> Are Arduino sketches/programs classed as a firmware?

TLDR

More of a domain language.

avr-gcc which includes avr-g++

So Ardunio (arduino-1.8.8) is C++ 11 (-std=gnu++11) but without any standard libraries so it can have optimised versions that consume less memory and are safer from leaks.

Yes an Arduino program/sketch would qualify as a firmware.

C++ IDE

Non C++ IDE

Arduino IDE 1.8.8
https://marketplace.visualstudio.com/items?itemName=vsciot-vscode.vscode-arduino
Arduino IDE version 2.0.0-beta.3

arduino-is-cpp.ino

void setup() {
  Serial.begin(9600);
  while(!Serial){}
  Serial.println(__cplusplus);
}

void loop() {}

Output

Verbose compiler output

/home/peter/downloads/arduino-1.8.8/arduino-builder -dump-prefs -logger=machine -hardware /home/peter/downloads/arduino-1.8.8/hardware -tools /home/peter/downloads/arduino-1.8.8/tools-builder -tools /home/peter/downloads/arduino-1.8.8/hardware/tools/avr -built-in-libraries /home/peter/downloads/arduino-1.8.8/libraries -libraries /home/peter/Arduino/libraries -fqbn=arduino:avr:uno -vid-pid=0X2341_0X0043 -ide-version=10808 -build-path /tmp/arduino_build_342783 -warnings=none -build-cache /tmp/arduino_cache_309119 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.avr-gcc.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avr-gcc-5.4.0-atmel3.6.1-arduino2.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA-1.2.1.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude-6.3.0-arduino14.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -verbose /home/peter/downloads/sketch_may15a/sketch_may15a.ino
/home/peter/downloads/arduino-1.8.8/arduino-builder -compile -logger=machine -hardware /home/peter/downloads/arduino-1.8.8/hardware -tools /home/peter/downloads/arduino-1.8.8/tools-builder -tools /home/peter/downloads/arduino-1.8.8/hardware/tools/avr -built-in-libraries /home/peter/downloads/arduino-1.8.8/libraries -libraries /home/peter/Arduino/libraries -fqbn=arduino:avr:uno -vid-pid=0X2341_0X0043 -ide-version=10808 -build-path /tmp/arduino_build_342783 -warnings=none -build-cache /tmp/arduino_cache_309119 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.avr-gcc.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avr-gcc-5.4.0-atmel3.6.1-arduino2.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.arduinoOTA-1.2.1.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -prefs=runtime.tools.avrdude-6.3.0-arduino14.path=/home/peter/downloads/arduino-1.8.8/hardware/tools/avr -verbose /home/peter/downloads/sketch_may15a/sketch_may15a.ino
Using board 'uno' from platform in folder: /home/peter/downloads/arduino-1.8.8/hardware/arduino/avr
Using core 'arduino' from platform in folder: /home/peter/downloads/arduino-1.8.8/hardware/arduino/avr
Detecting libraries used...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10808 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/cores/arduino -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/variants/standard /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp -o /dev/null
Generating function prototypes...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -flto -w -x c++ -E -CC -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10808 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/cores/arduino -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/variants/standard /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp -o /tmp/arduino_build_342783/preproc/ctags_target_for_gcc_minus_e.cpp
/home/peter/downloads/arduino-1.8.8/tools-builder/ctags/5.8-arduino11/ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/arduino_build_342783/preproc/ctags_target_for_gcc_minus_e.cpp
Compiling sketch...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-g++ -c -g -Os -w -std=gnu++11 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -Wno-error=narrowing -MMD -flto -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=10808 -DARDUINO_AVR_UNO -DARDUINO_ARCH_AVR -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/cores/arduino -I/home/peter/downloads/arduino-1.8.8/hardware/arduino/avr/variants/standard /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp -o /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp.o
Compiling libraries...
Compiling core...
Using precompiled core: /tmp/arduino_cache_309119/core/core_arduino_avr_uno_dbe74caced8262d937c72ad4123d41cb.a
Linking everything together...
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-gcc -w -Os -g -flto -fuse-linker-plugin -Wl,--gc-sections -mmcu=atmega328p -o /tmp/arduino_build_342783/sketch_may15a.ino.elf /tmp/arduino_build_342783/sketch/sketch_may15a.ino.cpp.o /tmp/arduino_build_342783/../arduino_cache_309119/core/core_arduino_avr_uno_dbe74caced8262d937c72ad4123d41cb.a -L/tmp/arduino_build_342783 -lm
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-objcopy -O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 /tmp/arduino_build_342783/sketch_may15a.ino.elf /tmp/arduino_build_342783/sketch_may15a.ino.eep
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-objcopy -O ihex -R .eeprom /tmp/arduino_build_342783/sketch_may15a.ino.elf /tmp/arduino_build_342783/sketch_may15a.ino.hex
/home/peter/downloads/arduino-1.8.8/hardware/tools/avr/bin/avr-size -A /tmp/arduino_build_342783/sketch_may15a.ino.elf
Sketch uses 1634 bytes (5%) of program storage space. Maximum is 32256 bytes.
Global variables use 188 bytes (9%) of dynamic memory, leaving 1860 bytes for local variables. Maximum is 2048 bytes.

Research links

Arduino Forum - Changing/Finding Out The C++ Compiler Version
Wikipedia - Wiring (development platform)
- More of a domain language.
- > The Wiring IDE includes a C/C++ library called “Wiring”, which makes common input/output operations much easier. Wiring programs are written in C++.
Wikipedia - Processing (programming language)
- > Processing has spawned another project, Wiring, which uses the Processing IDE with a collection of libraries written in the C++ language
- This is where the confusion comes in around Java. However this is only relevant to the Processing language which isn’t what Arduino uses.
  - > Written in Java, GLSL, JavaScript
  - > When programming in Processing, all additional classes defined will be treated as inner classes when the code is translated into pure Java before compiling.
Wikipedia - Arduino
- > The Arduino IDE supports the languages C and C++ using special rules of code structuring. The Arduino IDE supplies a software library from the Wiring project, which provides many common input and output procedures.
Stack Overflow - How to program an Arduino with C++
GitHub - ladislas/Bare-Arduino-Project
Arduino Forum - What is the difference between std::string and String
Stack Overflow -Strings in C++ class file for Arduino not compiling
Arduino Forum - Error #include <string> while compileing

.NET Conf focus on F# notes

Wed, 16 Mar 2022 20:14:19 +0000

.NET Conf: Focus on F# notes

Yes this has been sat in my drafts for far too long. I suspect since 2021-07-29

JavaScript backend
Supports .NET libs
Supports LINQ
Has pipes, is this similar to what we have in bash and unix?
Prefers type inference.
- Total opposite of C# which prefers explicit type definition to cut down on run time errors.
- How to use python type hinting?
- Carl Meyer - Type-checked Python in the real world - PyCon 2018
- TypeScript
Looks like a scripting language.
F# interactive in VS Code.
let keyword much like TypeScript.
I wonder if it will replace TypeScript in some applications.
F# for Fun and Profit
- Why use F#?
  - > F# is not cluttered up with coding “noise” such as curly brackets, semicolons and so on.
    - https://fsharpforfunandprofit.com/posts/fvsc-sum-of-squares/
    - Reminds me of what I was saying here: A state of .NET in late 2020 - C# 9
    - Perhaps C# 9 is actually getting lots of ideas from F# however I think there needs to be a clear line between them otherwise you muddy the two languages.
SAFE Stack
- ASP.NET + F#
- Fable compiles F# to JavaScript.
- React for client.
- Sharing custom types between server and client.
- Sharing validation between server and client.
Alt + enter for dotnet fsi repl run current selection
Dotnet fsi… where is C# fsi? Integrate csi to dotnet cli #17666
Haskell vs f#…

Visual safety development

Sun, 20 Feb 2022 16:16:19 +0000

Visual warnings when developing on multiple environments

It is common for a developer or sysadmin to have access to multiple environments or servers such as production (live) (server-1), test (staging) and perhaps localhost (server-2).

The problem with this is that it’s easy to forget which environment you’re using.

One solution would be to have a mental pre-check of “am I on server X… yes I am” before running any commands that perform changes (writes/updates). However this is bound to fail you one day.

Another solution is making a visual clue appear which makes it clear consciously or subconsciously which server you’re using.

SQL Server Management Studio (SSMS)

Server 1 connection pane. In this example server-1 is our live production environment.

Server 1 connection options.

Server 2 connection pane. In this example server-2 is our localhost environment.

Server 2 connection options.

Here is the server list on the left. Top one is localhost (server-2) and bottom is live production (server-1).

Running a SQL query against server-1 shows us the nice warning at the bottom.

Running a SQL query against server-2 shows us we’re safe.

Insomnia REST

I use Insomnia which is like Postman for my API testing. I have various environment variables such as URIs which get swapped out based on environment.

Live environment shows red as a warning.

Staging environment shows orange as a warning.

Localhost environment shows green as we’re safe.

Linux SSH

From my .bashrc I deploy on remote servers and local machines.

if [ "$color_prompt" == yes ]; then
	if [ ! "$SSH_CLIENT" == "" ]; then
		# If this is a ssh session then change our PS1 colour to let them know it's remote.
		PS1='${debian_chroot:+($debian_chroot)}\[\033[01;33m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
	else
		# If this isn't a ssh connection then use our normal colour PS1.
		PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '
	fi
else
	PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

Green for local.

Yellow for remote.

Citroen Berlingo maintenance

Thu, 10 Feb 2022 17:52:19 +0000

Citroen Berlingo maintenance

Rear load space light

I wanted to check how the extra LED lights were hooked in.

Looks like the previous owner tapped into the main lighting circuit which comes from the BSI unit (Body Control Unit).

Auxiliary belt

Checking auxiliary belt condition.

Can see the bar code so that’s a good sign.

Pollen filter

It was a very finicky job to get the old pollen/cab filter out as it was stuck behind the plastic lip. You can see the amount of debris that came with it.

Old vs new filter. A massive difference.

I think I could grow a tree from that.

Battery

The new Varta 12 v 60 Ah 540 CCA battery.

I cleaned the battery holder.

Interestingly the positive lug has a quick connect/disconnect toolless fastener. Useful for long term storage of the vehicle. I cleaned off the old anti rust petroleum which appeared to be water logged.

Similar situation with the negative although slightly inaccessible.

Battery cover got a clean up too.

This is the old Varta. Interestingly I didn’t note the old battery brand before purchasing a replacement. Anyway it’s 12 v 640 CCA with 60 Ah.

At first the distribution seemed like it would get in the way but actually it’s easily moved aside. Anyway overall it’s useful since you get a few high amperage fuses to tap off from. 30 A and some 50 A fuses come as spare.

Adding the red cover keeps the water off.

The socket for the battery holder is a 10 mm. You will need a socket extension or two.

Rear breaks

Socket size required for “wheel nuts” is 17 mm. I noted the actual bolts are the removable part, this is something other vehicles do backwards which makes it a pain when the nuts are stuck and the bolts need drilling.

An example of the tools required.

They actually thought about this. I like it. Nice tie point supplied for holding the calipers.

Quite a big difference in old vs new pads.

Driver side rear disc looks fine.

Passenger side rear disc looks fine.

Key fob

I had to replace the battery in my key fob. Interesting antenna design on the PCB.

Looks like there is a separate RFID (passive) device on the board which handles immobiliser. It works regardless of the battery.

Previously I found wrong information when looking up the replacement battery type online. This is the actual battery I had.

I needed to replace my fey fob outer plastic shell. The spring mechanism to flip open the key is rather tricky to replace. I suspect it wasn’t intended to be replaced since the new shell came with a new key blank. I wanted to swap in my existing key. Here I have laid out the exact orientation of how the parts nest.

Notice the orientation of each part. They must nest a particular way. It feels like it could nest 2 ways but ultimately it only works in the correct orientation.

Inserting the key.

Inserting the coupler part.

Here I am showing how the button fits onto that coupler, for reference purposes it is without the spring.

Closer look at the orientations. What you would need to do is put the spring in then pretension it since there is a grove in the case and button that locks the spring in place at each end. You need to ensure the locking of the spring is so that it’s around 45 degrees forward from the position you need to insert the button. This means you rotate the button 45 degrees back roughly to tension that spring so it’s trying to rotate forward when it’s pushed down into position. Thus locking the assembly. When the button is later pressed the coupler moves allowing the button to rotate forward bringing the key with it until it’s at its un-tensioned position. You should only test that with the top cover on or while holding the button otherwise it could spring out into your face.

New finished shell top.

New shell bottom.

Previous old shell with nasty buttons.

ISM GSM band mesh networking LoRa

Sat, 27 Nov 2021 16:42:10 +0000

Bristol LoRa disaster.radio

This post has been sat around in my drafts for a long time (since 2020-01-23) before I posted it and therefore may no longer be relevant.

I thought I better get on and post this now as a flurry of videos about LoRa have surfaced again.

I ordered two of these in the 868 MHz variant from AliExpress: LILYGO® TTGO Disaster-Radio LoRa32 V2.1 1.6 Version 433/868/915MHZ LoRa ESP-32 OLED 0.96 Inch SD Card Bluetooth WIFI Module

They come pre flashed with the disaster.radio firmware.

Just did some range tests and had really impressive results of 700 m with one unit in hand on foot and the other on a shelf in the QTH second floor.

I suggested some improvements to the project. Below is a couple of my suggestions/bug reports along with related links:

Routing table error after long uptime or 3+ nodes #38
disaster-radio-website/issues/4
868 Mhz setting for Europe #43 Sam raised the ticket but this is something we discussed in the “Bristol LoRa” WhatsApp group.
releases/tag/0.2.0
Useful docs on the protocol
What is lora?

Also see

esptool for flashing the LoRa boards
My blog post on Arduino package management mentioning platformio
Bristol HAMNET and 2E0PGS - HSMM-MESH since we’re semi the same group.

DV4 CCTV file format conversion

Thu, 09 Sep 2021 20:16:10 +0000

How I processed CCTV custom DV4 file format into MP4

Exporting

I found my DVR required a FAT32 MBR formatted file system USB stick or USB HDD.

Part files

The files when exported from the CCTV will split at 2.1 GB into part files once the clip exceeds 2.1 GB in size.
You will need to reassemble them before making a MP4.
Turns out these can simply be concatenated together into one large blob: cat filename*.dv4 > filename.cat.dv4
Real example: cat CH04_2021JAN01000000_1.dv4 CH04_2021JAN01000000_1.part02.dv4 > CH04_2021JAN01000000_1.cat.dv4
VLC didn’t work on raw DV4 files. mpv does and so does ffplay.

Conversion

After reassembling the part files you need to then do a container copy: ffmpeg -i filename.cat.dv4 -c:v copy -c:a copy -y filename.cat.dv4.mp4
Real example: ffmpeg -i CH04_2021JAN01000000_1.cat.dv4 -c:v copy -c:a copy -y CH04_2021JAN01000000_1.cat.dv4.mp4

bulk-process.sh

Below is just a script to bulk process the concatenated files in a batch as it’s rather time consuming if you have more than one camera channel or date range exported.

#!/bin/bash

for i in *.cat.dv4; do
		ffmpeg -i "$i" -c:v copy -c:a copy -y "$i".mp4
done

WRT54G NVRAM WiFi drop outs

Tue, 31 Aug 2021 17:00:19 +0000

Flashing WRT54G with OpenWRT causes WiFi drop outs

When swapping between firmwares (stock Linksys, Tomato, DDWRT, OpenWRT) you may find the WiFi drops out.

I thought it maybe a temperature issue or even hardware issue. I tried cooling fans and heat blown across the PCB and I tried various pressure across PCB in case there was a loose solder joint.

If you experience this try doing a full wipe of the NVRAM as flashing firmware doesn’t fully clear down the NVRAM.

You can try the 30/30/30 reset but that never got me anywhere. I had to use a software method.

Look up firmware specific ways. Some use the GUI and some use the command line, see the below examples respectively:

“Erase all data in NVRAM memory (thorough)”

erase nvram

WRT and router off topic notes

WRT54G still useful as a 10/100 Mbps router for NAT separation or translation.
BT routers don’t seem to have the ability to use the WAN port with a local subnet gateway so WRT based stuff is still a good tool in the network engineer/sysadmin toolbox.
Checkout the GL.iNet GL-MT300N-V2 and various other GL.iNet products. They’re useful as a mini firewall, router, data diode or WiFi AP and supports/has pre-installed OpenWRT.

Small van comparison

Tue, 31 Aug 2021 07:21:19 +0000

Comparison of various caddy/combo small vans

Sorted ascending order load area length

Also highlighted for my goldilocks zone.

Name	Body style	Height	Width	Length	Volume
Fiat Fiorino	Combi van	1,205mm	1,473mm	740mm	1.3m3
Ford Transit Connect	L1 Double Cab In-Van	1,237mm	1,533mm	861mm	1.2m3
Fiat Doblo Cargo	Short low-roof Combi	1,250mm	1,261mm	950mm	0.79m3
Renault Kangoo	Maxi crew van	1,154mm	1,145mm	1,008mm	1.3m3
Ford Transit Connect	L2 Double Cab In-Van	1,267mm	1,496mm	1,061mm	1.6m3
Nissan NV200	Combi (five seat/seven seat)	1,358mm	1,500mm	1,160/510mm	2.3/0.9m3
Peugeot Bipper	Van	1,178mm	1,473mm	1,164mm	2.5m3
Fiat Doblo Cargo	Long low-roof Combi	1,250mm	1,261mm	1,300mm	1.05m3
Fiat Doblo Cargo	XL long high-roof Combi	1,950mm	1,261mm	1,300mm	1.1m3
Mercedes Citan	Dualiner	1,255mm	1,460mm	1,337mm	2.4/3.7m3
Mercedes Citan	Compact	1,258mm	1,460mm	1,369mm	2.4m3
Renault Kangoo	Standard van	1,251mm	1,219mm	1,476mm	4.0m3
Fiat Fiorino	Standard van	1,205mm	1,473mm	1,523mm	2.5m3
Mercedes Citan	Long	1,258mm	1,460mm	1,753mm	3.1m3
Volkswagen Caddy	Caddy	1,257 mm	1,556mm	1,779mm	3.2m3
Vauxhall Combo	L1 short wheelbase van	1,236mm	1,630mm	1,781mm	3.3m3
Ford Transit Connect	L1 Short wheelbase van	1,269mm	1,543mm	1,786mm	2.9m3
Peugeot Partner	Standard van	1,236mm	1,550mm	1,817mm	3.3m3
Citroen Berlingo	M standard van	1,236mm	1,550mm	1,817mm	3.3m3
Toyota Proace	L1	1,200mm	1,527mm	1,817mm	3.3m3
Fiat Doblo Cargo	Short low-roof van	1,305mm	1,714mm	1,820mm	3.4m3
Fiat Doblo Cargo	Long high-roof van	1,550mm	1,714mm	1,820mm	4.0m3
Renault Kangoo	Maxi van	1,252mm	1,219mm	1,862mm	1.4m3
Nissan NV200	Van	1,358mm	1,500mm	2,040mm	4.2m3
Vauxhall Combo	L2 long wheelbase crew van	1,243mm	1,527mm	2,110mm	4.0m3
Vauxhall Combo	L2 long wheelbase van	1,243mm	1,630mm	2,131mm	3.9m3
Mercedes Citan	Extra Long	1,258mm	1,460mm	2,137mm	3.8m3
Ford Transit Connect	L2 Long wheelbase van	1,269mm	1,496mm	2,152mm	3.6m3
Peugeot Partner	Long van	1,243mm	1,550mm	2,167mm	3.8m3
Citroen Berlingo	XL long wheelbase van	1,243mm	1,550mm	2,167mm	3.8m3
Toyota Proace	L2	1,200mm	1,527mm	2,167mm	3.9m3
Fiat Doblo Cargo	Long low-roof van	1,305mm	1,714mm	2,170mm	4.2m3
Fiat Doblo Cargo	XL long high-roof van	1,550mm	1,714mm	2,170mm	5.0m3
Volkswagen Caddy	Caddy Maxi	1,262mm	1,556mm	2,249mm	4.2m3
Fiat Doblo Cargo	Work-Up pick-up	1,368mm	1,818mm	2,300mm	1.54m3
Vauxhall Combo	L1 with FlexCargo	1,236mm	1,630mm	3,090mm	3.8m3
Peugeot Partner	Standard with Extenso	1,236mm	1,550mm	3,090mm	3.9m3
Citroen Berlingo	M with Extenso	1,236mm	1,550mm	3,090mm	3.9m3
Peugeot Partner	Long with Extenso	1,243mm	1,550mm	3,440mm	4.4m3
Citroen Berlingo	XL with Extenso	1,243mm	1,550mm	3,440mm	4.4m3

Size of items

So we know if the van can fit a UK single size mattress for camping:
- YOUR GUIDE TO UK MATTRESS SIZES
  - Single: 90 cm x 190 cm
  - In mm: 900 mm x 1900 mm
6 ft is 1828.8 mm
Medium size equipment rack is 1400 mm

Things of note

A lot of the vans now have PSA engines, quotes from AutoExpress:
- > Proace City model, which is another PSA joint-venture offering, this time a rebadged version of the Citroen Berlingo, Peugeot Partner and Vauxhall
- > Development was led by the Citroen Berlingo and Peugeot Partner which arrived in 2018, with the Vauxhall Combo arriving in 2019 and the Toyota Proace City arriving in 2020. They all use the same running gear and are largely identical from the leading edge of the bonnet all the way to the back doors.
- > The Fiat Doblo used to have a platform sharing partner in the shape of the Vauxhall Combo. But with that model now part of the PSA Group, the Doblo soldiers on alone.
- > The Renault is a versatile urban delivery van that majors on being good to drive and delivering impressive fuel efficiency. It’s also great value for money, and shares much of its engineering with the Mercedes Citan
  - Citan and Kangoo share the same running rail?
Observed vans with tailgate windows:
- Volkswagen Caddy
- Citroen Berlingo
- Fiat Fiorino
- Mercedes Citan
- Peugeot Bipper
- Peugeot Partner
Small vans like this are often called LCV
Common rail fuel injection.
- Volkswagen adopt common rail.
> One area where the Citan is a bit of a letdown is the quality of the materials on board. This isn’t like Merc’s cars with plush materials everywhere, instead the cabin has the look of the Kangoo

Review links

MPG links

YouTube review links

Portable data layer library

Wed, 11 Aug 2021 08:43:19 +0000

Portable data layer library

Needs to work with dependency injection. E.g. Consumed in large MVC Web application.
Needs to work without dependency injection. E.g. Consumed in small console application.
Needs to use Dapper ORM. Lightweight, fast and simple.
Needs to be portable. We are building a .NET Standard library so why ruin the portability with specific references or tightly coupling to dependencies.
I want it to work with SqlConnection, SQLiteConnection and possibly other connectors. Therefore it should be not overly specific.
Should be async but can also provided non async methods.

Research materials

My previous attempts at this.
SQLite + Dapper = Simple Data Access Layer
SQLiteDemo
Dapper in ASP.NET Core with Repository Pattern – Detailed
Repository Pattern C#

Research analysed

Numbered points correspond to “Research materials” respectively.

When I first started using Dapper I created a simple repository design pattern lib. However it didn’t work well for dependency injection and had references to specific dependencies. I wanted to make this truly universal so I can apply it to future applications.
Doesn’t show namespaces or folder structure so lets look at the actual source. See point 3.
Has hard coded file paths. I like the use of a base repository and class inheritance. Has interfaces which is good for DI. Seems excessive to check SQLite file existence on every call. Make use of using which is good practice. Folder structure is slightly off.
Makes use of UnitOfWork pattern which is powerful but potentially overly abstracted. It depends on dependency injection and assumes configuration strings. It demos how to implement the DI which is nice.
Very much based around Entity Framework and other large framework design with requirement of DI. Does however give a nice example of using repository pattern from end to end.

Specific issues

There is some old code which has monolithic design and cross database talking. The new data layer library needs to be a bit flexible around this. So originally there was namespace separation with this hierarchy.

Namespaces

MyOrg.SpecialApp.Models.DbOne.CustomerModel.cs

MyOrg.SpecialApp.Repositories.DbOne.CustomerRepository.cs

MyOrg.SpecialApp.Models.DbTwo.UserModel.cs

However this makes referencing items messy and solution explorer navigation a mess of expanded folders. For example inside the repository CustomerRepository you would have to reference Models.DbOne.CustomerModel. Why specify the context which should be default.

Improved is

MyOrg.SpecialApp.DbOne.Models.CustomerModel.cs

MyOrg.SpecialApp.DbOne.Repositories.CustomerRepository.cs

MyOrg.SpecialApp.DbTwo.Models.UserModel.cs

Now inside the repository CustomerRepository you can reference Models.CustomerModel and all the bits your likely to work on are under one folder too.

I also found it useful to postfix Repository to the end of the repository classes so it’s immediately obvious they’re not a model. Then when intellisense suggests a variable you have a nice await customerRepository.GetByIdAsync(1);

Design notes

It’s all part of engineering.
It’s not uncommon to come up with solutions which work but can be improved upon with hindsight.
Another thing is business or project requirements change over years.
We could spend 4 weeks over engineering something simple then come to replace it in years to come or we can implement what looks good in 2 days and replace it if required.
It could also take many years to find a short coming with a particular design pattern.

Project examples

2E0PGS/user-trak/src/master/UserTrak.Data/ (SQLite)
2E0PGS/always-watching-bot/src/master/AlwaysWatchingBot.Data (SQLite)

Project example with interfaces for DI scenarios

TODO: MVC or Web API project example.

Folder structure example with interfaces

|   AlwaysWatchingBot.Data.csproj                 
|                                                 
+---Interfaces                                    
|       IAttachmentRepository.cs                  
|       IMessageRepository.cs                     
|                                                 
+---Models                                        
|       AttachmentModel.cs                        
|       MessageModel.cs                           
|                                                 
\---Repositories                                  
        AttachmentRepository.cs                   
        BaseRepository.cs                         
        MessageRepository.cs.cs                   

One repo per a table at the moment, you can use UnitOfWork pattern to combine that into one large object.
One base repo per a database, normally only one DB per a microservice but if you got monolithic or multiple DBs then you can seperate each DB using namespaces above the three main namespaces.
TODO: Show multi DB example.
TODO: Show example interface class for DI as I don’t have a public repo with one in.
TODO: Simple injector example?

Connection string setup examples

ASP.NET Framework example with SQL Server connector (Startup.cs)

Data.Repositories.BaseRepository.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["MyMicroService"].ConnectionString;

ASP.NET Core example with SQL Server connector (Startup.cs)

Data.Repositories.BaseRepository.ConnectionString = Configuration["ConnectionStrings:MyMicroService"];

.NET Core Console example with SQLite connector (Program.cs)

Data.Repositories.BaseRepository.FilePath = _configuration["sqliteFilePath"];

DI examples

ASP.NET Core example (Startup.cs)

services.AddSingleton<ICustomerRepository, CustomerRepository>();

ASP.NET Framework example (Unity Container) (UnityConfig.cs)

container.RegisterType(typeof(ICustomerRepository), typeof(CustomerRepository));

container.RegisterType<Data.Interfaces.ICustomerRepository, Data.Repositories.CustomerRepository>();